If you're upgrading your DotNetNuke instance, here is a list of simple steps to follow during the upgrade process.
First tip, test the upgrade on a staging site first, pull a copy of the database and files down, try the upgrade, make sure all your functionality is still there. Then upgrade production (backup everything first)
Here’s the steps to upgrade
1. Backup the database.
2. Backup the file system.
3. Make sure you did 1 & 2
4. Extract the latest DNN ZIP file somewhere, i usually use the installation package, not the upgrade package out of preference.
5. Edit the web.config file from DNN package
a. Modify the SQL connection strings, there are two places, you can get the string from your original web.config
b. Be sure to copy the Machinekey ValidationKey and Decription key values from your original web.config file
c. Double check the DatabaseOwner and ObjectQualifier values in the web.config file, if you changed them in your original web.config file you’ll need to change them in the new one.
d. Make any other changes to the new web.config that you added to the original config file, anything your custom modules required? codeSubDirectories node perhaps?
6. Copy the new files, including the changed web.config file, over the old files.
7. Load the website, this will cause the upgrade to begin when the page loads. Make sure the upgrade process completes successfully.
8. At this point you should be done.
Like I said, test first, just to be sure you have everything working properly.
Hope these steps help, I've upgraded many a DNN website, and even a few today.