Upgrade error: Could not load file or assembly Microsoft.Web.Extensions, Version=1.0.61025

I have upgraded from Beta 2 to RC1 and followed all of the upgrade instructions, but I'm still getting this error:

Error 26 Could not load file or assembly 'Microsoft.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

I'm aware that Microsoft.Web.Extensions is now System.Web.Extensions, but I can't find where the old reference is!!!

I have searched all the files in my project for "Microsoft.Web.Extensions" as well as the machine.config. I'm currently searching every file on my hard drive for this reference and still can't find it.

Any ideas?

Thanks,

Still looking for some help...
Do you have the ControlToolkit on your site? We had that error before we updated to the newest toolkit.

I've found you have to move the DLL files form the .NET version folder on the hard drive to the bin folder in the site otherwise they need to be in the GAC.

I'm finding other problems with it. Like [no relevant source code lines] gotta be permissions or something.

Still looking...

I have the same problem and finally found out that the reference to Microsoft.Web.Extensions is in my web.config.

Have to go through and changes all "Microsoft.Web" to "System.Web" (mainly under the<pages><controls> tag).