Could not load file or assembly 'Ajax' or one of its dependencies. The system cannot find the file specified

The additional error message with it is:

I have been facing this error where as i have also included ajax library in my website. Also web.config also has important tags regarding ajaxtoolkit.

Please 开发者_如何学运维keep in view that I have recently switched this website from ASP.NET 3.5 to 4.0

Please help on this....

Also here is Stack Trace:

Assembly Load Trace: The following information can be helpful to determine why the assembly 'Ajax' could not be loaded.


WRN: Assembly binding logging is turned OFF.
To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1.
Note: There is some performance penalty associated with assembly bind failure logging.
To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].

I just ran into this issue when trying to upgrade an old app to ASP.NET 4.0. I know - still old but this is what the client wanted. Went around and around as to why this was happening. And then I found it. The app was using the ASP.NET 4.0 Classic app pool in IIS. When I switched to ASP.NET 4.0 Integrated the error went away. Hope this helps someone else with this issue.