11 Feb 2011
13 Apr 2011
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Just encountered this error and fixed it so thought I'd share the solution and hopefully save anyone some headaches.
Basically this occurs when choosing to do a solution rebuild in Visual Studio. VS removes some dll from the bin directory and you will then be presented with the above error when browsing the site.
To fix this, replace the bin folder from a svn repo if you have one. Alternatively create a new sitefinity project and copy the bin folder from that and copy it into your project. One thing to remember is to back up your site's bin folder.