Something is missing in the CRM app GAC.  I am not a developer, but from this message is suspect - the installer fails to add a file. After Upgrading CRM from 3.0 to 4.0 and upgrading Scribe from 6.1. to 6.2.2 the Publisher failed.  The message from the Scribe Publisher is: 

“[FileNotFoundException: Could not load file or assembly 'Microsoft.Crm.Platform.Callout.Base, Version=3.0.5300.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.]“

I poked around on the on the server and found that the Microsoft.Dynamics.Platform.Callout.Base.dll is missing or hidden. The assembly needs to be found and added to the GAC in order for Publishing to work. And an  IISRESET reset should be run.

I looked on the installation DVD in \server\i386\GAC (unless it’s a 64-bit machine) for missing .dlls that need to be added to the GAC.  The version number surprised me, but that’s the one on the 4.0 DVD. 

Pierre is currently rockin' to " Not Forgotten [Radio Version][*]" By: Israel & New Breed - on the  Alive in South Africa Disc 2 album.