Canon Scanner – Unable to open TWAIN source

I have a Canon CanoScan 4400F Scanner and the other day I was unable to get it to work.  I use the Canon software CanoScan Toolbox to operate the scanner and when trying to scan I was getting the following error message:


CanoScan Toolbox
Unable to open TWAIN source
Please check connection
Then re-start Toolbox

Searching the Internet for this problem turned up several people having the same problem and several solutions which looked like they may or may not work.  One of the recommended solutions was to make sure a certain folder path is in your PATH environment variable.  As it turned out this was the problem, so here is how to add that path back into your environment variables.

First, determine the correct path to add into the PATH environment variable.  Look in C:\Windows\twain_32 and there should one other folder in there.  In my case it was  named CNQ4803.


This is the path that is needed to be added into the PATH environment variable.



Now, follow these instructions to get to the dialog to modify the PATH environment variable.

Control Panel > System > and then choose Advanced System Settings in the left hand column.


This will bring up the System Properties dialog (it should already be on the Advanced tab).


At the bottom of this dialog is an Environment Variables button.  Clicking this button will bring up the Environment Variables dialog.


In the bottom panel, scroll until you find the variable named Path.  Select this one and then hit the Edit… button to bring up the Edit System Variable dialog.


In the Variable value text box, scroll all the way to the right and then add in the path C:\Windows\twain_32\CNQ4803 that was determined earlier.  Make sure to separate this value with a preceding semi-colon.  And also be careful not to make any other changes to this value.

Now OK your way out of all of the dialogs and CanoScan Toolbox will now work as expected.



  • Jeff: I want to thank you SO much for this information. I've had my 4400F about 2 years; today was the first time I had ever run into this 'twain' problem. For some reason, it has, many times in the past, 'lost' something in the CanoScan Toolbox. That only required uninstalling and reinstalling the Toolbox software. Anyway, I followed your instructions and all is fine now. Thanks again.

  • jeff - many thanks for the are a true gentleman

  • Jeff - many thanks for your time and help.
    Perfect solution.

  • Me Too!
    My canon LiDE 70 has been working fine for years. I recently installed Roxio Creator 2010 and I believe it is what munged my path. This fixed worked when reinstalling the drivers and CanoScan did not. Many Thanks!

  • Fixed my scanner after reading this. Thankyou.

  • I've also started running Win 7 64-bit and this scanner simply will not work with it. This fix did not help. I've been working on it for days and am just going to give it away to a friend and buy another scanner. Anything but a Canon.

  • Jeff, this worked! I spent the whole morning checking blogs and the Canon site. Thanks so much for sharing ...

  • Thanks for your help it resolved my problem.

  • Big thanks. I was about to do some reinstall and was saved by this post!

  • Mucho Gracias Senor Jeff! apparently an Oracle XE installations messed my path.
    God Bless!

  • veeeeeeeeeery thanks

  • Jeff!! Thanks a bunch!!!!!

  • When Canon's miscreant CanoScan app suddenly stopped working with my 8400F scanner, I tried everything else I could think of but nothing worked. Rebooting, system restoring, reinstalling the app, reinstalling just the driver, running in compatibility mode, yada, yada. Nothing worked.

    Then I discovered this page. This worked. Thank you!

  • Thanks for the solution - this did the trick!

  • This method works on my CanScan Lide 30. Thanks!

  • you are simply great!

  • Thanks Jeff - fixed my cannon 4200F which stopped working (unable to open TWAIN source) One of my recently installed apps. must have corrupted the PATH variable. Now working OK. Thanks again.

  • Thank you Jeff! This fixed the issue with my canoscan 656u not working on Windows 2003. I had to use Windows 2000 drivers for it, but that's besides the point. Putting the Twain_32 folder in Path variable was the solution for me.

  • I tried the above solution for my FB630u Canoscan on a Vista system. It worked like a charm. Thank you so much.

  • Thank you very much!

  • Thanks very much, Jeff! Also works with the 4200F on Windows 32-bit Vista Home Edition.

  • Thank you so much! Finally got the scanner working!

  • Absolute legend!! Why this isn't simply found when updating drivers etc on the Canon site.

  • Thanks a lot! Worked fine for LIDE 35 on Vista Ultimate 32bit.

  • Brilliant. This fixed it for Windows 7 64 Bit.
    Looks like Acronis backup software install messed up the path variable.
    Due to the wide range of apps that seem to mess up the path settings I wonder if its a windows bug or if the canon install doesn't format it correctly in the first perhaps it needs a trailing ;

  • Thanks a million! Solved my issue--thought I was going to have to finally upgrade scanners but now I can hold out longer.

  • Unfortunately, it didn't work for me... It tells me that "Release the lock switch, detach I/F cable and reconnect. Scanner driver will be closed." than it gives the TWAIN error. I read something about a black-and-white bar near the front controls which the scanner uses for aligning, and that the problem might be that it is warped somehow. Anyone knows something about this problem, or preferably, to fix it? I have a lide 25...

  • Thanks, for advice. :-)

  • great.
    fix my problem. Thanks

  • I feel unlucky. This did not work for me after upgrading some Intel WIFI drivers. The "path" details you mention arleady have some Intel thing in it so I added what you said seperated by a semicolon but still get the error message. what do do next? Thanks in advanced. Am using W764-bit. Should I use 64 instead of 32 in the text? Also, I have the LIDE25

  • OK, I'm bad. Want to update for future readers with same specifics (W7 64bit and LIDE 25). I had input the wrong LIDE model in my path edit. Left it at 32 for 32 bit and the scanner works. Whooo hooo! Hooray!

    P.S., should I change to 64 intead of 32 in the text edit? Are the drivers really 64 bit? I installed the latest complete software package from the Cannon U.S. support site. The description says its for W7 64 but if one tries downloading the driver serprately it is only for 32 bit. Can Cannon be any more bad at support?

  • Thanks! Did work for me.

  • Thanks, it worked for me on a Canoscan LiDE25 after two days lost and Canon unable to help.

  • This is simply awesome. It works fantastic for my CanoScanLide25. Thanks a lot. I have been figuring out for the whole night.


  • I tried this and it did not work. I have been using the scanner for several years and have been able to reload it and use it successfully on a new Vista system. Suddenly it stopped working.

    The existing path appears quite strange to me and is as follows:

    C:\Program Files\CommonFiles\ArcSoft\Bin;%SystemRoot%system32;%SystemRoot%;%SystemRoot%\System32\Wbem

    ArcSoft is the photo software that I am working with. But it won't work directly from the CanoScan Toolbox either.

    I tried adding C:\Windows\TWAIN_32\CNQL30 directly after adding the semi-colon and then by adding a semi-colon and a backslash. Neither worked.

    Any other ideas?

    Thanks for helping

  • Thanks you so much for the tip. My Canon LiDE 500F worked fine for years and one day I got this TWAIN error. I tried uninstall a few times but it still didn't fix the problem until I found the solution on your site. Good sharing!

  • Thanks, this worked for my Canon LIDE 25!

    Windows 7 Ultimate is my OS, and although I couldn't get Canon's own CanoScan Toolbox to work, I was able to get Windows 7's scanner driver operational with the above. The only difference was my TWAIN file path, I had to add this to my PATH setting:


    After a reboot, my CanoScan LIDE 25 is working once more.

  • thanks you very much. I tried many method from many forum but cannot make my scanner work. But this time, the problem solved.

  • Help, I think I messed up the entire path line accidentally. How can I fix it? Do you have the entire text that should be there??

  • Jeff,

    Thanks so much for posting this fix. It was not obvious why the scanner would have failed after working for a couple of years. I just wonder, how did you find this out?

  • Many thanks Jeff,
    My daughter in Australial mailed me with the problem, I contacted my son (the wizz kid) in Sweden & he sent her the link. the fix is done and now I get the scanned documentation I needed.

  • thanks a lot!
    i can't find any infomation about the problem in Chinese! So i arrive at here through Google, and it works! 太好了!

  • Thanks - you saved me from buying a new scanner!

  • Thanks a lot. I've had this scanner for a couple of years - and encountered this problem for the first time today (of course, when I needed it to work urgently). Luckily, I ran across your solution first and am back up and running now.

    Once again, Thanks a million!

  • Thanks a lot from Copenhagen, Denmark

  • Thanks for your instructions - got my Canon scanner working a treat!

  • Thanks for the information so much...

  • Fantastic, worked like a charm on my Windows 2003 Server 64-bit. Like with many others, this problem just happened recently with the CanoScan working great before. In any event, the solution worked super well for me. Thanks a ton!

  • Thanks Jeff, luckly found this page quickly LIDE70 fixed in no time on both XP and Vista computers!

  • Jeff, you Sir, are a Gentleman and a Scholar, a million thanks, excellent walkthrough and worked an absolute treat, once again many thanks.

  • Wow! Brlliant fix! Thank you!

  • YOU ARE THE BEST!!!!!!!! THANKS WORKING FINE NOW!!!!!!!!!!!!!!!!!!!!!!!

  • Thanks, it worked for me. Not sure how it worked over the previous years! I updated the drivers from the Canon site but that did not help. The Path addition was the needed fix.

    Gary Davis

  • I have just had this problem. File CNQ4803 is in the C:\Windows\twain_32 folder.

    I just tried to edit the path, but only got as far as Control Panel and System and Security.

    I have no advanced settings tab in my system and security menu.

    Re-installing the programme does not help as I continue to get the same message.

  • Man, you are a lifesaver. My 4200F stopped working after upgrading to Win 7 SP1. I was on the verge of throwing out the scanner and buying a new one. Thanks.

  • Canon driver self-installs in c:\canon not c:\windows\twain. I copied it to \windows\twain and pathed it . . . nothing different

  • Thanks so much!
    I have a Canon Lide 25, my path to twain is:

    After putting it into path variable scanner get working again!

  • This path worked great with my CanoScan 4200F: C:\Windows\twain_32\CNQ4200


  • Running Vista Home Premium. My CanoScan N1220U, about 10 years old now, is only used it a few times a year. Like everyone else has experienced, it just stopped working! Added the folder to the system path and it started working again. Thanks!!!
    I can't imagine that something just took it out of the path. I doubt it was ever there to begin with. Must have been some system configuration change or other service pack that mucked up Twain, but what do I know. Regardless I'm glad its working now, saved me a trip to Staples. Thanks a million!

  • Apologies if this is redundant, I didn't read through the entire thread. Win7x64: use Canoscan Toolbox v4.9, not v5.0. For some reason the newer one doesn't work, but the older one does (5.0 might work on 32-bit, don't know). Install the driver first (SetupSG.exe) (look for 8400fvst6410231a_64en [32en for 32-bit, I would think]) then install the Toolbox (csbwin4932en). You might have to use Jeff's path variable trick; I did that before all the rest and I didn't go back and test without it, so YMMV. Once everything is done you will need to reboot before everything will work. A good tool for testing and troubleshooting is to download Irfanview, which has Twain and scanning tools under the File menu. Enjoy!

  • Geez, forgot to say that I'm using an 8400f - procedure might work for other older models too.

  • I just want to say thank you.

    My canoscan lide 70 works like charm.

  • I have a canoscan 4200F and it worked before I installed W7 (x64) SP1 but not since. I tried this and it doesn't work.

  • Hi Jeff. Thanks very much. I have spent hours with unistalling and reinstalling the Canon drivers and software to solve this problem which made no impact. I tried your solution on my XP system and it worked perfectly. Thanks again.

  • Thank you so much!!!
    My Canoscan Lide 60 is working again and your instruction made it fast and simple. Great!

  • Great helpful post!

  • Muchas gracias! me ahorraste mucho trabajo!

  • damn. this left me two months without home scanner after a reinstall to Win 7. Thanks a lot for the trick.

    Why can't the installer add the path itself. Or why is it necessary to have it in the PATH variable in the first place.
    But I gess we can be lucky Canon provides 64 bit drivers for such old products.

  • Another satisfied customer.

    PATH add was my answer for an LIDE35 on Windows 7 (32-bit).

    Thanks, Jeff!

  • I have been doing this sort of stuff a long time, and when I come across someone who gives such a precise and effective answer, I find it truly awesome. thanks so much for your efforts.

  • Thanks for your help!

  • Thank you, this work fantastically! I can stop swearing at my scanner now...

  • Thank you, it worked for me. Only the puzzle is why the problem appeared. It worked for more than one year without any problem.

  • Hi Jeff,

    Thank you very much for the clear and concise instructions, it helped to fix the error quickly.


  • Thanks mate, got my Canon LiDE 25 working again.

  • Thanks! This fixed also my Canon F4200 with Windows XP with same problem.

  • Thank you so much!

  • Thank you so so much! By your advice, I've fixed my Canon LiDE 60 with Windows 7 with the same problem. Now I am enjoying the great performance of my scanner again!

    I'm so grateful to you!


  • thank you very much

  • I used your info to fix my old Canon LiDe scanner. It was great to find this solution on the internet. It really works! Thanks for keeping this info out there for us to find.

  • Awesome! Finally I can scan with my FB630U with Vista and Picasa.

    thanks for the info!

  • Thank you very much for the info. I was going to buy a new scanner. Imagine that.

    You just saved me some bucks

  • Thanks for the blog entry. Solved my problem.

  • As with the others, thanks so much! {Jonathan}

  • Cool, thanks a lot. Took me a hour to get the Scanner running on x64.

  • Solved on win7 x64!

  • Thanks Jeff for the information regarding the "path". Unfortunately it did not work but together with the comment from Elliphant on June 28: use canoscan v4.9 in stead of v5.0 I got my scanner 8400f working again.

  • Jeff - Now it works ! :) THANK YOU
    CanoScan 4200F & Win7 x64

  • Hey there, this didn't work for me unfortunately, I have a Canon N670U and it suddenly stopped working about a month ago saying its unable to open TWAIN source, do you have any other ideas? Thanks, Jackie

  • Hi Jeff,
    Thank you so much. This helped me with CanoScan 8400F.

  • I was unlucky - didn't work - still: many thanks.

  • Hi Jeff,

    Thanks! Quick easy fix! Canoscan LiDE 60

  • Big thanks Jeff! CanoScan 4400F. Used to work fine for years. Suddenly stop working today. Don't know how the environment variable got changed. Windows update maybe?

  • I wish I had found this years ago. Finally my Canoscan 8400F works and with both Canoscan Toolbox and Picasa as well.

  • You are magnificent! Working perfectly now.

  • Thanks Jeff - it didn't fix my CanoScan D1250U2F problem but your instructions were really easy to follow and made me feel less frustrated nevertheless!

  • Thanks Jeff it fixed the problem on my CanoScan LiDE 600F

  • YES IS FIXED, this works on Windows 7, no in XP

    En XP no se arreglo nada, pero en Windows7 si funciono

    Thanks a lot!!!

  • Hiya Jeff, I was wondering if you could post that entire pathway plz because I accidentally deleted the pathway instead of just adding to it. I went to press the arrow on my laptop and pressed wrong button grrrrrrrr, could you help plz thanks

  • Hi CheekyKelz,
    Unfortunately the PATH variable is specific to your computer; as new applications are installed, new paths are added. At a minimum it will include this:


  • Yep, worked for me too! Cheers Jeff.

  • Thanks Jeff! Your kindness in posting this solution is STILL helping people out! After installing a new Canon multi-function printer, my old Cannon 9950F scanner stopped working with the error described. (It's got a long scanning bed, so I want to keep it.) It now works again after following your instructions. Thanks again!!

  • Thanks! That fixed it for me too!

  • I could Kiss you! you absolute legend!

  • No luck for me, but awesome this has worked for so many people. I am trying to setup CanoScan LIDE 50 on Windows Vista Home 64 bit. Very annoyed at Canon for being so unenvironmental - imagine all the scanners that just go to landfill because people can't figure this stuff out.

  • Thanks for your help!
    Jeff for President!!!

  • You just saved my bacon.

  • Great help. Thank u so much

  • Thank you very very much! Made my day!

  • Thanks so much,
    after reading so much different threads and spendings HOURS of other solutions (including a complete Factory re-set),

    this worked liked nothing ...

  • Excellent!!!!!!!!! Worked great.
    Thanks a lot.

  • Many thanks! Don't know how this PATH got lost...

  • Thanks Jeff, our Lide 60 is back working again on Windows 7!

  • I have a Canon CanoScan 5200f

    I Did exactly as you instructed...I also double checked and did a restart... but unfortunatley the exact same problem persists...'unable to select TWAIN source'

    I have Windows7 64bit...i first downloaded and installed driver from CNET then found the tool box exe elsewhere and installed in 2-steps...perhaps this is the issue as when using the toolbox it always asks to select source after which the issue arises...any thoughts on this one???


  • Hi Rick,
    Try downloading the latest version of the Windows 7 64-bit Canon software from Canon's website:


  • Thanks for the help, saved my day with my CanoScan 5200F

  • thank you so much for this!

  • Thanks a lot Jeff
    This was great and solved my problem immediately

  • Thanks. This fixed the problem I was having with my Caonn MP800 and the MP Navigator software as well. It would just give me a "Scan failed" every time.

    I eventually figured out it was a TWAIN problem by looking at %temp%\twain.log which had "CloseServer - Why Can't We Find The Thunker Window?" but didn't know how to fix it.

    Lo and behlold, I added the C:\Windows\twain_32\MP800 directory to my PATH and it works again!

  • Hi Rick,
    It looks like the 5200F is a European model only which possibly could be the problem with installed a US version of the software (but that is just a guess). If you still are having problems try this link from the Canon UK downloads:


  • Many thanks. Path variable was the issue

  • Windows 7 64 bit and a Canon 5200F. I had this problem, and went nack to the Canon 4.9 Toolbox, and with your path set, - it worked. Thank you.

  • Win7 64-bit and a CanoScan LiDE 25. You saved my life, thank you!

  • Thank you so much!

  • Windows 7, 32 bit, Canoscan Lide 90. Used to work fine until now, when I had to replace my HD on my computer (it also doesn't work w/my new netbook, Windows 7 starter 32 bit). I think it might have to do with the new 5.0 version - I had been using 4.9 or earlier, I think, with no problems.

    I looked for the C:\Windows\twain_32 folder and found two CNQ folders in there (2411 and 2412). I tried inputting the path for one, then the other, but neither worked. Should I put in both?

  • It worked!! Better than some of the other solutions that are out there. Thanks so much.

  • Wow. I was reinstalling my driver everytime i come across this problem. Now its fixed forever! Hopefuly.
    Thank you so much for this wonderful article! ;)

  • That workded. You're a saviour.

  • Hi I need your help!!!

    I'm using canoScan 8400F.
    I followed your instruction but the window still pop out:

    Unable to open TWAIN source
    Please check connection
    Then restart toolbox

    Any advise?

  • Thanks for the info! Much appreciated and saved me the hassle of the usual uninstall / reinstall / repeat cycle!

  • Thanks for posting this! I've wasted a LOT of time trying to figure out why my scanner no longer wants to scan and this fixed it in less than 5 minutes. I wish I had found it sooner.

  • Thanks for posting this. It was really a lot of help. At last I am able to successfully scan my document.

  • Thank you so much, it works!!!

  • fantastic, I have tried everything but nothing worked until I tried your way.. thank you!

  • Thank you. I've been looking for a solution for quite some time.

  • Worked like a charm. THANK YOU. I still don't know how my path variable got erased, but who cares, it's fixed now.

    For those that have scrolled this far but for whom it didn't work, first install your driver, then go looking for its folder in C:\Windows\twain_32 (yes, even Windows 7 64 bit puts it in a folder called twain_32). When you find it's folder name, then add that as described above - each scanner model has a different folder name.

  • hi im using canon ir2318, also i am trying to set up my scanner i also had the same problem. is this procedure is applicable for me. thanks

  • This solved the problem. The problem had NOT occured on a different computer running an identical OS (XP SP3), but with older hardware. Was dumbfounded as to why the error appeared on the newer computer. Thank you!

  • Thank you very much!!! This works fine for my CanoScan 4400F!

  • Kudos! Two and a half years later, and the info is STILL valuable. Let's hope this entry stays around as long as it's needed. BTW, this method worked for me on Windows XP and LIDE 80 combo.

  • Thanks! worked for me - Win 7/64, Canon 8600F

  • I have tried every one of the above fixes for a Win7 Home 64bit installation, even upgraded PhotoStudio 5.5 to v6.0 and still get the same error "Unable to select TWAIN source".

    We have uninstalled everything and started from scratch, still in the wilderness with this scanner.

  • Thanks so much for making my day easier. Worked perfectly on CanoScan LIDE 60 on Windows 7 64 bit os!

  • Thank you so much!


  • Jeff - your trick is still working - thank you so much for such a clear post on this.
    Best wishes

  • Awesome! Worked for me too!!!

  • I confirm this one too!!

  • Worked for me! Thank you very much!

  • Works for canon lide25

  • Thanks SO much. What can I say, it worked!

  • Just want to say thanks a lot for this! Google definitely put the most helpful answer at top of list!

    To confirm, this works in the UK for a CanoScan LiDE 70 on a Dell OptiPlex 990 running Windows 7 Professional 64 bit. I used CanoScan Toolbox and ScanGear CS driver 12.11 from Canon's website.

  • thank you vry much its was vry helpfull to me and if it wasnt u i would hav failed in my project.............

  • Reinstalling the software didn't fix the problem, but your solution did. You saved me a major headache, Thank you so much!

  • You're awesome. And then some!!!

  • I think this is still the definitive source on the internet for solving this problem. Thanks!

  • I tried your fix on a Canoscan LIDE 30 (with win7), but it didn't work. After much fiddling I finaly reached the goal. First: The driver ScanGear CS v7.0.3.1a did work all the time (I could hear and see it when information was exchanged with the scanner and the scanner started up). The problem was my newest toolbox program. Some time ago I downloaded CanoscanToolbox4.932en_win7-Vista-xp.exe from Canon site. But this program was not able to find the driver, no matter what I did. Instead I installed CanoscanToolbox_v4.136enVista.exe and it worked immediately :-)
    Nice to see that your advise have helped so many people! :-)

  • Seems to have worked for me too Jeff. Running a 4400F under Win7 32bit. Problem appeared a month or so ago and likely to have been Win7 SP1 or installation of Adobe Photoshop/Premiere Elements 10 that caused it as both changes happened about the same time. Have been puzzling since then (though still able to acquire scans through Photoshop so thought problem was Toolbox rather than driver). Then found your posting - what a hero!

  • Thanks a lot for this solution, I have the same problem with Canon LiDe 60 on Win7/64b. I have changed many types of drivers, try compatibility modes etc. Now I am knocking my head against the wall ;) Everything is ok now. It works. Thank You again.

  • Thanking you so much for the advice...I added the environment variable and it fixed it.

  • Wow, you know how much time I wasted on this until i found your tip!! Very long phonecalls with Canon helpdesk, emails with them, no one could help me.
    Thanks you very much!

  • You would think that Canon would know this!
    Thanks very much!

  • found this solution just five minutes before buying a new scanner .... I suppose that Canon don't want to provide such an easy solution rather than providing new scanner hardware to increase their profit ....

    Thank YOU!

  • Brilliant - Thank you SOOOOO much. It's amazing that in April 2012 this is still a problem that is so simply solved and is not listed on the Canon website as a solution. You are my new hero and you don't even need to grab the nearest tablecloth to wear it all week as a cloak with your underwear outside of your trousers:)

  • It Works !!!

    thanks a lot !!

  • It Works, thanks you so much!

  • Absolutely worked! You saved me a lot of grief. Thanks!

  • I've been using W7 64-bit operating system on my laptop for about 18 months. My scanner worked perfectly until last week - Suddenly I started getting "Unable to open TWAIN source" error. I couldn't find or do anything to get it to work until I found your very well explained fix. Many thanks

  • Another success. I was going to toss this hand-me-down LiDE30 in the trash. No need now to buy a new one. Thanks.

  • I can't seem to find any folder within the TWAIN folder, I can only find the "wiatwain.ds" file, nothing else. Any one know why?

  • Great post !! Thanks

  • Running LiDE 70, Canon Toolbox on Win7 x64. Path fix did NOT work as others have reported for this version.

    But here's what DID work: run the Canon Toolbox app as Administrator. It's working for me without doing anything with path.

  • Worked great for my CanoScan 4400F on Windows 7 Ultimate. Thanks!

  • Jeff,

    Thanks for posting this article! I could tell that both my drivers and the application to drive my older Canon f9950 were installed and functional... but it did not occur to me that the PATH (or lack thereof) would be the culprit in the failure to "communicate". Win 7 Home Premium.

  • Many thanks for the solution it is rare that such precise advise is found on the web

  • Hello Jeff,

    thank you very much for posting this solution, it worked out fine for me.

    I own a Canon LIDE500F scanner and run Win 7 64.

  • man, thank you so much, after long time that i wanted to buy a new scanner i could use it again :) god bless you

  • ur an absolute genius dude !!!! u solved my problem in a jiffy !!!!

  • Fantastic straight forward information! My CanoScan LiDE 60 stopped working for some reason. Now, it is working again!

    I wonder why the CanoScan toolbox isn't able to handle this issue or at least return a meaningful error message!

    Because, obviously this trivial problem is causing trouble and time loss to thousands of users.

  • After a reboot worked like a charm!.
    Many thanks.

  • You the man! Thanks for the quick/easy fix!

  • Thanks!!!!! Fixed my LiDE 25 on Win 7 x64

  • Wow! This fixed my issue too on WinXP SP3 for Lide 600F. Thanx for the tip!

  • Brilliant! Thanks for the screen shots too! We technically challenged need all the help we can get.

  • Jeff, you are a star *. Fixed my canon Scanner LIDE 600f on Windows 7. Thank you very much.

  • Lide 25 users with windows 7.
    Exactly same problem after setting this additional directory to my path environment variable. :(

  • You, sir, are a life saver. Worked perfectly on Windows7 (64-bit) with a Canoscan 8600F.

  • I spent half an hour installing/reinstalling drivers, searching new versions etc, because it didn't work.

    Then I discovered your page, and after one minute my Canoscan lide 25 is back to life !

    Thank you so much !!

  • Thankyou for the solution. Thanks for the quick/easy fix!

  • You are an absolute genius! Spent months researching this and saw something on another forum but not as clearly explained as this!


  • Thank you very much, It worked for me: to install the Canoscan Lide 25 on Windows 7 x64. I had been trying the solution from the official Canon and windows websites, it was not working. I had been trying various solution found on the internet: in vain. You solved the problem. Thank you.

  • You are great, works like a champ.THANK YOU

  • Scanner worked like a charm for many years and then suddenly stopped working. I suspect some recent Windows 7 upgrade or other software clobbered the PATH. The PATH solution worked for my LiDE 60! I am computer programmer with lots of experience and it would have taken me a lot of time and so you saved me a lot of headache!

  • Thanks, I was holding on fixing this for days before I googled this.. Today I didn't have my wife's laptop to use my scanner and didn't have a choice but to find a solution. This tip worked for me (Win 7) and many thanks..

  • thanks, thanks, thanks.
    Canoscan Lide 600F - Vista Ultimate x64

  • Thank you very much...

  • Yep, you helped me too! Woot! Thank you so much!

  • Yay!

    Just bought a Win64 laptop, and I must have installed, uninstalled, and re-installed the software and drivers a dozen times. Rebooting like a madman didn't help, either. Just a simple addition to the path and all is well.

    Thank-you thank-you thank-you.

  • Great!
    I was fighting with this bothersome problem for years. I installed and unistalled drivers and Toolbox I don't know how much times and sometimes it didn't work..
    And now with this simple trick it's all ok!
    Really thanks so much

  • You're a diamond geezer! Thanks so much.

  • awesome. Thanks a bunch. this fixed it for my Lide 70 :-)

  • I must have installed & uninstalled Canon's drivers a dozen times on my new computer, but the TWAIN scanner was not recognized on my Canoscan 8600F.

    Finally bumped into your page on a Google search & poof it works great!

    Thanks for posting a simple, but very effective fix!

  • Another satisfied customer. Fixed my problem in 2 minutes!

  • Thanks, it solved TWAIN problem at 4400F right away!

  • Thanks. i've lost two hours installing and uninstalling damn drivers and software :)

  • Worked like a charm!! Thank you for providing the step by step!

  • Thanks! After a Windows update and some other installs, my scanner suddenly started presenting this error dialog. Adding the twain path fixed it.

  • No luck here. Modified the path variable, but still getting the error. Windows 7, 64 bit, Canon CanoScan 8400F.

    CanoScan Toolbox

  • I modified Path and it seemed not to work, but I had to close and re-launch Photoshop, the destination application.
    Then all was well! (LiDE 25, XP)
    Thanks for the solution.

  • Thank you so much :)

  • Bingo! Thanks a lot.

  • Many Many Thanks.
    It works great, I was disappointed but .... ;)

  • Don't know if this has already been posted, but for Windows 7 64-bit users, CanoScan Toolbox 5.0 does not work, but 4.9 does.

  • Perfect! Worked like a charm, thank you!

  • This was a huge help. Thanks!

  • many thanks!

    Did it very fast.

  • Excellent, concise solution. Thanks!

  • Hi,

    thanks for a perfect hint.

    My configuration: Windows 7 64x, LiDE 500F

    At first adding the path did not help.

    Then, I tried varous things (like not starting WIA service, checking the limit of PATH variable length, starting the Toolkit as admin/ in compatibility mode, ...).

    Eventually, I noticed that in the PATH variable, all items are separated with semiolon ONLY.

    I removed the SPACE after the semocolon before my path to the twain drivers.

    AND IT WORKS - [amazing that] this matters in the 21st century - my goodness.

    All those who posted that the hint did not help, chech please for the extra SPACE .-)

  • Thanks! Got my scanner operating quickly. Such a simple fix, but so deep in the details. Amazing.

  • Thank you so much! It really helps me!!

  • Worked great. Mine was a Canon 500F, and the file was ;C:\Windows\twain_32\CNQL500

    Note no spaces

    Thanks alot, this saved hours of heart ache. Canon owes you a beer!

  • Thanks a bunch! This worked for me as well with a Canon 4400f on Windows 7 x64.

  • You save my day Jeff! Why Canon did not have this kind of information and let its customer setting in the dark?! In all Canon support forums and portals, no word even mentioned about this particular disdainful problem.

  • Wow - this is the first time I have had success with online help!! Many thanks!!!!!!!!!!!

  • That did the trick. But what I don't understand is, why it suddenly got this point. Thanks for the help.

  • Got it working now. Can't understand why it used to work but then decided not to. Good job there's young people like you who can find out how to sort it.

  • WOW! It works. Thanks a lot.

  • Many thanks, I spent 2 hours searching the internet in vain for a solution until I found this page. Now I got it working. Shame on Canon for ignoring this problem.

  • Thank you sir. This was very helpful.

  • Thank you !!!! Life saver !!

  • It's people like you that actually help the world go round.

    Been trying to get a LiDe35 to work under W7 64Bit for 6 months and this was the missing bit, Thank you sooo much

  • Thanks so much.
    However, it is unacceptable that one needs to do manually what should be done automatically.

  • It's a CanoScan LiDE200, and I'm running Windows XP. I followed the directions *exactly*.

    Good directions, by the way.
    Pity they didn't work, though. Absolutely no change to the twain error message.

  • Thanks for this. Worked great with CanoScan 4200F

  • Thanks! I thought I'd have to buy a new scanner to replace my aging Canoscan LiDE 500F, but this worked a treat. I'm amazed that people such as yourself go to so much effort to create step by step instructions like this for the rest of us. Thank you for your time, effort and knowledge.

  • Mil gracias por la solucion inimaginable desde mi experiencia pero dio con la solucion!! gracias buena solucion.. saludos
    canon scan lide25 en win7 64b

  • Thank you so much!!! It really worked on my PC. Now I can use my scanner canoscan 4400f.

  • Thanks. Saved me buying a new scanner.

  • Thanks it works , you was save me

  • Thank you very much for solving this annoying thing! More than one year I was using older computer for scanning only...

  • This was extremely helpful, had no problems until today and have owned the scanner 6 months. This helped me solve the issue quickly.

  • Thank you for posting this fix. I finally got my Canon lide35 scanner to work in W7 64-bit after using the lide60 driver and your path instructions. Glad that I can still use this old scanner which was a really good model.

  • Thank you so much for your article. Made my day :-)

  • You Jeff are real star :) :)

    Works unter Windows 7 Home Premium

    NOTE to everyone: Do not try to run the LIDE 500F via an USB Hub on Windows 7, that does not seem to work properly and Windows has major issues to reach the CanoScan.

    Uninstall driver at System Config, then Add Path as mentioned above, plugin Scaner DIRECTLY at Computer/Laptop - restart, reinsriver from Canon Website - restart once again, enjoy!

  • Tried the path thing to no avail. Running Win 7 Premium on Dell Latitude Laptop. Scanner is a LiDe 600F. Tried uninstalling drivers etc etc - nothing. Reading back through all the comments I found one which said much the same but got it to work by running Canoscan as Administrator and voila! it worked ...about 3 hours wasted. Clearly it has come about from a Windows update!

  • I had just about given up expecting to use my Canoscan 4200F on Win 7 64-bit Home Premium. Last year I read heaps of advice, mainly about deleting old drivers and installing the latest version from Canon, but all to no avail. Today I had another bash at it, was just about to throw in the towel again, and then found your page. yes, adding the variable to PATH was all that was needed. Why couldn't Canon get that right?

    Thank you VERY much indeed.

  • Worked like a charm, thanks!

  • Thanks, Happy new year

  • THANKYOU THANKYOU THANKYOU! I was on the phone with Canon support for over an HOUR, and they did not know this. Just changing the path worked!!

  • Setting PATH didn't help me either. Running Toolbox as Administrator helped me.
    Thanks for this article.

  • Muchas gracias desde Chile

  • Perfect solution to the problem. It worked like a charm.

  • Many thanks, very simple and WORKING solution. It helped me very much.....

  • Jeff,
    Thanks a lot for your solution. It fix my frustation in using my CanoScan 4200F in Windows 7 x64. It perfectly works as expected.....

  • Fixed my 8400F under Windows 7 x64 and Photoshop CS2. You're the man.

  • I thought I'ld never be able to use my 4400F to scan slides again after upgrading from Windows XP to 7. Until this morning when I found your solution. Thanks a lot !

  • Tahnks Jeff!!!
    have a 600f scanner work great my folder was name 4802 instead of 4803 changed the 3 for 2 and away we went. Thanks

  • Thanks a lot, to others please, check all zour steps again ... I forgot to write semicolon and was not working ... then read again and check all step by step now is working , thanks again

  • Thanks Jeff!
    This is the solution for my old Lide 60 scanner.

  • Thank you very much for this information!

  • This worked for me, old CanoScan LIDE60 scanner on Windows 7 Enterprise 64-bit. Thanks!

  • Thank you very much! I would never have figured it out. CanoScan 8400F

  • ABSOLUTELY WORKS! I was going to buy another scanner! Thank you!

  • Quick, easy, simple and makes my scanner work again!

  • You got me setup right - you da man!

  • Thank you so so so very much!!!!! I did not understand what i was doing, but i followed your instructions and it is working now!!! :)

  • That did it! Wish I would have found this a couple of years ago!

  • Many thanks - very helpful!

  • Thanks for this information. I have been trying to get my Lide70 working and this resolved my issue. Cheers.

  • I have a 500F and if you follow his instructions, it should work!

    Windows 7 64 bit
    Path: C:\Windows\twain_32\CNQL500

    Double check yours...

  • THANK YOU SOOOOOOO MUCH... Huge help!!!! Thanks for your time and being such a great help...Cheers!!

  • thanks so much for posting this information

  • This worked and you are a genius...thanks so much!

  • Worked for me. Many thanks!

    CanoScan LiDE 500F
    Windows 7 64
    Path: C:\Windows\twain_32\CNQL500

  • Thanks for this info! This has been biting me for a while - some windows update or something stuffed up my Canon LIDE600F Scanner on Win7/x64, and no amount of reinstalling seemed to fix it. This works a treat! :)

  • thanks a million! Canon wasn't even able to fix this for me.

  • Thanks so much. Worked for me.

  • Great job! FANTASTIC! Many thanks from Italy.

    (CanoScan LiDE 600F Win7 64bit)

  • Thanks so much - this solved the problem which I have had for almost a year, since I went over to Windows 7 64bit!!!!

  • Thanks for sharing this! Many thanks for fixing my LiDE 25.

  • Jeff your solution have been working for years!. I installed my CanoScan 8600f on a new laptop which came with Win 8 X64 and confronted with the same problem. your solution worked just fine. Many thanks.

  • Thank you so much for this info. My Canon 4200f now is working properly

  • Yeah ..... it worked.
    My 4400F was unusefull without canoscan toolbox.

    Tks a lot


  • Thanks a million!! it works!

  • i have the same twain source problem but on canon lide 60.....does the posted insrtuctions apply to lide 60 ?

  • I have the same problem with my Canon D530. It worked fine with my lap top, I just a new computer with windows 8 (I hate windows 8) on it, and I have to keep restarting the computer to get the scanner to work. I tried what the canon support people told me to do, but that did not work. I changed the path like you said above, but it it still is not working right. If I keep right on scanning it is ok, but if I stop for a while it will no longer work without restarting the computer. I am very frustrated.

  • Thanks a lot! Working!!!

  • Got it fixed thanks to you!

  • Awesome - Worked Perfect. Thanks.

  • Thanks, very useful info.

  • Our Canon scanner has periodically had issues requiring us to reinstall the software. But we just moved the scanner to a new computer, installed the software and then started getting the "Unable to Open Twain Source" error message.

    Your fix worked like a charm. Thank you for taking the time to create such detailed instructions!

  • Hey. Thankx a LOT! Sweet spot!

  • Thanks, this fixed my scanner problem too.

  • I tried Jeff's fix in the past and it didn't work, but after coming back and reading the comments, I tried just installing the newer version of the CanoScan Toolbox ver. 4.9 that's been updated for Windows 7. IT WORKED! Here's the website: The download box is near the bottom. Again, don't use Toolbox 5.0, it didn't work for me (Win 7 64-bit). Thanks to everyone with their input! My beloved Canon LiDE 25 are reunited once more :)

  • I am trying for help again, the scanner works fine the first time in the day that I am using it. When I try to use it again a couple of hours later , it keeps saying the server is busy and to switch applications, when I do that it still says that the scanner is busy. (Canon D530) I am wondering if the store will take it back, because I am totally aggravated with it. I have tried posting several times, I see only the first post, not the consecutive ones, so I am not sure this is getting to you

  • This is the post that, after 3 1/2 years, just keeps on giving :-) Thanks Jeff

  • It didn't work for me. I am about to give up. When I first bought my canoscan9000F it worked beautifully with my Windows 7-64 OS. Now, immediately after scanning a photo, I get that stupid message, and then it stops working.

  • Wow, worked like a charm !!!

  • I also faced the same problem:
    CanoScan Toolbox
    Unable to open TWAIN source
    Please check connection
    Then re-start Toolbox

    I could not find any subfolder in C:\Windows\twain_32

    I tried installing the latest software from Canon website. Even that did not work. I then followed Amanda's instructions and it worked perfect.

    Thanks to you all!


    # Amanda C said on 08 June, 2013 11:41 PM
    I tried Jeff's fix in the past and it didn't work, but after coming back and reading the comments, I tried just installing the newer version of the CanoScan Toolbox ver. 4.9 that's been updated for Windows 7. IT WORKED! Here's the website: The download box is near the bottom. Again, don't use Toolbox 5.0, it didn't work for me (Win 7 64-bit). Thanks to everyone with their input! My beloved Canon LiDE 25 are reunited once more :)


  • Worked well. Thank you.

  • Another happy customer!

  • You saved my bacon......and that's all that needs be said.

    Heaven or Monaco, it's your choice.....

  • Thanks man! Got my Cannon Lide 70 working again!

  • Holy S*&T!! I've used my scanner for years with no problem. Then, all of the sudden, nothing. I literally had it sitting at my garbage when I found this and like magic it works again! You, sir, are amazing.

  • Canoscan 8400f now running on Windows 8 ! Thank You Elliphant for your advice in this thread.

    I had tried some other combinations of known 64-bit drivers for other models and different toolboxes, but ended removing it all and deleting the twain drivers in despair. Then I came back for one last shot and found Elliphant's link to the proper 64-bit Windows 7 driver - filename 8400fvst6410231a_64en - and installed Toolbox 4.9 - filename CSTb4931WNEN.

    Worked like a charm!

    BTW, I too had a fling with Toolbox 5.0 at another time, but couldn't get it to work and reverted to 4.9 with success. I'm through wasting time on /that/ experiment

  • Thank You! The only clean and precise documented solution for this problem.

    Canon: update your drivers !!!

  • Thanks a lot! It helped.

  • It works! Thank you!

  • Great job, it worked for me. Thank you

  • Canon LiDE 500F working fine in Win8_64 ONLY AFTER APPLYING this PATH solution (and Win7_64 drivers)! Thank you Jeff!

  • Thanks a lot! Working perfect

  • Thank you a lot! Helpful!

  • Brilliant! Works a treat! Thank you!

  • Worked for me, this is what I wrote: %SystemRoot%\system32;%SystemRoot%;C:\Windows\twain_32\CNQL25

  • You are my hero! Thanks a LOT!

  • Awesome! This article is fantastic - fixed it up :)

  • Thanks a million, after a couple of frustrating hours of misinformation, i found your article. Everything now working again

  • Wow! Thanks a lot!! My scanner now works:)

  • thank you

  • Thanks for the advice. I had to create a new path variable though, but it worked at the end. Much appreciated!

  • Hey Jeff, thanks a lot for the advice! Finally solve my Connection Problem!!

  • Hi Jeff, thanks so much for posting this solution! I'm not sure why this problem started all of a sudden. But I suspect it is related to a recent system 'cleanup' that I did

  • Thanks heaps! This worked a charm.

  • Worked like a champ. All I had to do after following the instructions was to restart the toolbox for my lide 600f

  • Good post, clear and direct!

    I only needed to read the first two lines. Why cant Canon have this on their knowledge base. WHY??? Because Canon, you can't!

  • I was just about to throw away my scanner when I came across this website. Thank you Mr. Widmer you just saved me from having to buy a new scanner.

  • Thank you! Problem solved. I can still use this scanner.

  • Thank you very much for this information! I would never have solved this without your help, and I am so happy to be able to use my scanner again. A very big thank you goes out to you from Sweden! //Mikael

  • Great, worked just fine. Many thanks!

  • Now my old Canon lide 25 works again.
    You were so precise in your solution, Thank you!

  • Great.. got it finally to work! Many, many thanks!

  • Another 4200F fixed, thanks!

  • This info us so usefull. My LIDE 35 (for Win7-64 use driver for LIDE60) was working for 2 years and then stopped. Now it is working again!! Thank you sooooo much.

  • Fantastic! It worked like a charm. many thanks

  • Canon MF3240 working great in Win8_64 AFTER APPLYING this PATH solution (and Win7_64 drivers)! Thank you Jeff!

  • Thank you kind sir! Worked like a charm!

  • Thank you - this is right solution for this problem!

  • It's 2013 and I know I should get a new scanner... but I think you just gave me a couple more miles with this one. Thank You!

  • Works for Canoscan  lide 35. THanks!!!!

  • Installed Visual Studio 2013 RC and my Canon Lide 25 stopped working.

    This solution worked for me, thank you

  • Help please! Even this perfect trick didn´t work.. I´m desperate! I have a CanoScan 9900F and it suddenly doesn´t want to work- like in many other cases.. But unfortunately Jeff´s advice didn´t help. I truly have no idea what to do now.. Does anybody, please, know another possible way how to solve it? Thank you!

  • Not just a Win7 or 64-bit problem - spent hours installing/uninstalling searching for bugs on a WinXP
    machine - til I found your comment, and bingo 5
    minutes later the scanner was up and running.

    A thousand-times thanks. Wish Canon would
    acknowledge this path bug.


  • Thanks, solved my problem

  • Excellent! Worked for me, thanks!

  • Thank you Amanda C - version 4.9 works for me when 5.0 did not

  • Thank you! Your post helped me fixing this same issue with my Canon 4200F on Windows 7

  • Problem solved. (CanoScan LiDe 25, Windows 7)
    Thank you, Jeff!

  • Thank you!!! This worked perfectly after I had spent a LOT OF TIME uninstalling and reinstalling repeatedly to try to solve my problem. Your instructions are excellent.

  • Thank you sooo much! After many unsuccessful tries I was considering buying a new scanner but then I found your blog and these instructions! Thank you!!!

  • Thank you very much! Worked perfectly for me.

  • this wasn't working until I kept scrolling through comments and found someone got it working with CanoScan Toolbox 4.9. It definitely wasn't working with 5.0 so I tried the older toolbox :D. Don't know now whether the path needed to be amended, but as it was already done I didn't bother to go back and take it out. CanoScan Toolbox 4.9 is working as it should with my Canoscan 5200F. Yay!

  • Thank you, I can finally use my trusty old Lide 60 again, so very clear and helpful!!

  • Wasted a few hours before stumbling over your advice here. It worked like a treat. Thanks for passing on the valuable wisdom. Certainly one to remember.
    Still a mystery why the path did not get added automatically though. All other devices were fine.
    Cheers and keep up the good work.

  • Thanks man, yo're the best :)

  • Thanks for the tip. You saved another scanner today! Great job!

  • Thank you! You saved my day!

  • Thank you very much. Works for me now. It's very helpfull.

  • Years later and still works! Thanks! You would figure the manufacture would figure this out! W7 64

  • Thanks you.

  • This worked fine. The scanner had been working propoerly for two years, then suddenly quit... this fixed it.

  • Ah man thanks a million - this is why I love the net
    you are a real time saver

    All the best man


  • Your fix worked!!!!! Thanks - I have spend many hours reloading programs looking for fixes. Now it works and in Windows 8.1. the screen shots made it so easy to make the changes needed

  • I followed your instructions and now it works. Thanks so much. I've had this scanner for a couple of years and this is the first time I've had this TWAIN problem.

  • it woks for the Lide25 too if you adapt the file name to CNQL25 like in the directory.
    Thank you so much from Germany and France for this help!

  • For the people who have a Lide30, and this didn't work (like for me):
    - Uninstall existing drivers and unplug USB cable
    - Copy the Vista drivers contents in the twain32 folder (resulting in C:\Windows\twain_32\CNQL30)
    - Plug in the USB cable,
    - Stop automatic driver install and browse manually to the twain32 folder
    - Do the trick, perfectly described by Jeff
    - Open CanoScan toolbox e voila!!! Works!!

    Thank you so much for this post, Jeff.

  • Today this worked for my LiDE 70. Thank you so much for this easy fix!

  • Incredible. Your instructions were clear and fixed the problem. You're amazing. Thanks a bunch!!

  • Huge thanks for your help - I had the same problem and the solution works a treat.

  • Excellent, thank you

  • WOW. I thank you for this. I used this for my LiDE25
    MOST IMPORTANT: don't forget the leading semi-colon.
    It is the first time I have been able to use my scanner-to-.pdf file on Windows 7 PRO 64bit!!!!

  • man you are a life saver!!!!!!now i have my 4 years old kid first hand writing saved!!!!!!!!!!!

  • Many thanks - brought my old scanner back from the dead :)

  • Many thanks - Worked for me too. Really clever fix mate!

  • Thank you so much for posting this! I've been very frustrated with my scanner. I've just got it working again on this computer after many months! Thanks!

  • Wow, that was not at all obvious but it worked like a champ with Win 7 Pro and a CanoScan 8400F. Thanks much!

  • Worked perfectly - thanks!

  • Fixed my LiDE 70! Has been working for years with no problems, must have been the recent MS SQL 2012 Express install that broken the PATH variable?

  • Perfect! I can now run my LiDE 70 scanner on my new Windows 7 laptop. Thought I'd have to buy a new scanner. Many thanks!

  • I encountered the exact same problem on Windows 7 Pro. Your path fix worked perfectly. Thanks!

  • Thanks, my LIDE50 now operates again on Win7 Pro :)

  • Thank You!!!

  • Another THANKS Jeff!!! Hip Hip Hooray! This fix did the trick on my Canon 8400F Scanner under Win 7 64

  • Many thanks for solving a most frustrating problem.

  • Thanks, worked great!

  • Many thanks for this. I had no idea that the "PATH environment variable" even existed. Isn't it a shame that both Microsoft and Canon can't be bothered to mention this on their websites!!!! Anyway, thanks again (I owe you a beer!).

  • Rather than one other folder, there were 3 folders in my C:\Windows\twain_32. I added all 3 to the path and this did not cure the problem; PhotoStudio 6 still cannot locate my 9000F (II) scanner and gives me the error messages about Twain. How do I determine which is the correct folder to add?

  • Thank you very much! Vielen Dank! Большое спасибо! :)

  • Many Thanks it worked with my cannon 8600f. In my case it was named CNQ4804. Does anyone know why this happens. Is it caused by Windows updates or new installations?

  • Further to my posting of 2 January. After setup I could use the scanner with Canon's Scangear, but PhotoStudio 6 could not find the scanner, even after doing all the things recommended above. On a hunch I uninstalled Photostudio and installed it on my laptop. Then, instead of installing the drivers with the CD as Canon strongly advise, I just plugged the scanner into the laptop usb drive, and switched it on. The laptop installed the driver (both machines run Windows7), and lo and behold Photostudio can now contact the scanner. Is this problem a cunning plan on the part of Canon to force everyone to use Scangear? I find Photostudio (which Canon used to supply free with their scanners) a much easier program to use. So: now if I want to scan I have to use my laptop. I can live with that.

  • Thank you1 4 years since the post - and it still works!

  • That's Amazing! Thanks for the info!

  • Much appreciated. Very clear, very useful.

  • YES. Many thanks.

  • Another thank you. Same as most people, Canoscan Lide 70 (O/S WIN 7 64) would not scan from toolbox. Knew it was a software issue as it would scan from Photoshop as a WIA but not Twain, but after that I had no idea. Reinstalling drivers did not work. Your very clear steps fixed it 1st time. Thank you!

  • Thanks! Why didn't the Canoscan software put the correct path in the first place? Weird.

  • Thanks much!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    Smart guy!

  • Thanks a ton! Works like a charm!

  • Bingo! Dragged out old Canon CanoScan5200F to scan old pictures into personal laptop (IBM T61p) and scan signed contracts into PDF's or work laptop (T410). Got error on T410. Canon support site gleaned nothing, first Google search hit your blog. Thank you very much!!!

  • Thank You!!!!!
    Not even the support of Canon was able to help me...
    And the Solution is so simple!
    They sent me the installation cd's but new install did not help.
    Just setting the path, and all is working.

  • Thanks a lot... You saved my day ...
    Best wishes from germany !!
    (Upgraded XP -> Vista -> W7/32Bit with Canon Lidl25 )

  • Thanks. that fixed the problem with my Scan Lide 35!

  • Fixed it immediately. Thanks for writing this up.

  • Thanks Jeff, fixed the problem straight away for my Canoscan Lide 25 (CNQL25) on Windows 7 which was working fine 2 weeks ago and refused to work today.

  • Thanks very much Jeff, worked perfectly!!
    Greeting from Bangkok

  • Thanks so much for taking the time to post this! Perfect solution.

  • Thank you, Jeff!
    It works now.

  • I've been rescued by this fabulous advice again. This time for CanonScan Lide 25 (I've had to downgrade due to power supply failing on my 5200F and haven't worked out what the problem is yet).

    But one tip. My computer has USB2.0 and USB3.0 whereas the Lide 25 is a very old USB lead. Guess what - I couldn't get the toolbox working, until I thought to swap leads with the 5200F. So just be aware of this added complication.

    thanks again for saving me!

  • Nice one - got my LiDE 500F working on Windows 7 64-bit. Tip: if you don't want to reboot after setting the path variable, open a cmd window and type: path=drive:\dir;%path%

  • Thanks! My scanner (LIDE 25) was always ready for the bin since I started using Win 7 x64 all those years ago as I always believed it wasn't supported..and now in 2014 I have a solution. :)

    So I can confirm, Win 7 x 64, this advice works!

  • Thanks

  • Jeff,

    Like so many others I just wanted to add my thanks.

    I have a Canon LIDO 600F and after spending hours trying to get it to work on a new Windows 7 x64 machine I finally found your blog which had the answer.

    You would think that Canon's Drive installation program would just add the correct Environment Path as part of the install process.

    Thanks again

  • Seems like I have a problem with every scanner I connect and I luckily keep finding this solution to my problem. Works every time.

  • Jeff,

    I'm a relieved owner of a Canon LIDE 70.

    Like some other folks who have commented, this did not work for me. Ah, but I kept digging. Here's what I managed to do:

    1. Went to Control Panel and uninstalled the scanner.

    2. Downloaded the driver ( win 7 lide70win641211ea15us.exe ) from the Canon website and saved it to a folder.

    3. Right clicked the file and chose Properties | Compatibility. Checked the compatibility box and chose Windows XP.

    4. Rebooted. On startup Win 7 installed another driver, and the scanner started humming along.

    5. Opened PSP 7 and entered scanner heaven.

    FYI, I actually went back and removed c:\windows\twain_32\etc. from the Path variable, rebooted, and the scanner still works!

    Hope this helps others,


  • Canon Lide 60. I have few different folders inside the C:\windows\twain_32 and one of them are: CNQ4807 and CNQL60. Imagine or not, but adding path to CNQL60 did not work :) so I added path to CNQ4807 too, following instruction and separated by semicolon, and it works !!!

    Thanks man, you are the MAN. I have this scanner for years and I love it but I wasn't able to use it on my new notebook. I tried few times and finally give up on it. Today I found this post. Miracle.

  • Thanks! Worked great with Windows 8 x64. For Adobe Photoshop CS6 you may need the Twain32 plugin

  • Thank you!!

  • Thank you so much! Worked great!

  • This worked for me as well with my Canon 8400F. Thank you so much!

  • Thanks from Serbia

  • Thanks a million!! It WORKED!!!!

  • BAM! - You are the man. Saved me a lot of troubleshooting. Thank you!!! :)

  • You've saved me from getting insane! Thanks so much!

  • Thanks, this fixed the problem. Like everyone else, my scanner was working great for years. I didn't use it for a few months and tried to scan a document and suddenly the TWAIN error popped up. After adding the correct path it worked. Feel better now.

  • MANY thanks. Works fine.

  • Just got a new computer and this fixed the issue. Really appreciate the post!

  • Hi Jeff, thanks for your post, i try this several times but a windows keep appears write unable to open TWAIN source please check connection then re-start toolbox. i try to add the path which is ;C:\Windows\twain_32\CNQL252 after C:\Program Files\Trend Micro\AMSP\
    but it still doesnt work for me, anyone can help please?

  • Same thing with Cano scan lide 25 and Win7 64. Man U R A GENIUS ! THANKS A LOT.

  • Jeff Tried it several times double checked everything and still doesn't work. Same problem and response as Lyvie.

    We still need help.

  • Thanks!!!

    Periodically I have hit the TWAIN problem but a reboot fixed it. Today after 3 reboots I was still unable to get the scanner working. Same TWAIN problem that you reported. I tried adding CNQxxxx to the PATH variable and now the scanner is working perfectly.

  • I am on Windows 7-32.

    I added the C:\Windows\twain_32\CNQL20 path as instructed. It still does not work.

    In the Environment Variable screen, upper portion, the Name in the Variable column is Path and the VALUE description is
    Either with or w/out a preceding semicolon, it still does not work.
    When I press SCAN in the TOOLBOX, a SELECT SOURCE screen pops up with the name of the scanner (LiDE 20/N670OU). When I press SELECT the usual message " Unable to select TWAIN sorce " appears. Also, when I press SETTINGS in the TOOLBOX, the SELECT SCANNER box is blank.

    Thank you for helping


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