I have encountered this error message in the past when I upgrade a few projects to 3.5 but it has been at least 3-4 months and found myself stuck with the same dilemma once again today. This error can be attributed to many things but mainly it comes down to web.config or ambigiouty in the references. Like my previous post, I would like to make another mental note as I know for sure that this won't be the last time that I will be seeing this error nor for anybody who upgrades to 3.5 that uses Ajax functionalities. After searching the web for answers, there was no definite response but after an hour of continuous searching, I was able to put all the information together which leads to the fix.
Here are the things that I tried and since that error message doesn't really dictate as to where the ambigiouty was found, I have to make a few guesses. The 4th bullet pretty much fixed my problem.
- I first removed references such as deleting them, then rebuild.
- I have to download the latest version of Ajax Control toolkit 3.5 to match the site version (3.5)
- One alternative that I have read is to rename the namespace into something different on controls that uses Ajax or AjaxControlToolkit but that would cumbersome if you have a lot of pages that uses Ajax. I found this method to be the least ideal.
- In the <controls> section of the web.config, commenting out the <add
Culture=neutral, PublicKeyToken=31bf3856ad364e35"/> section should do the trick.