CRM 2011 Error - Plug-in assembly does not contain the required types or assembly content cannot be updated.

When you try to import a solution you might get an error like this if you have turn CRM error mode to on. This most of the times occurs when a SDK step of the workflow have been deleted from the new assembly. You might have to find the step and then delete it manually on the importing server.

We came across this issue and was greatly helped by the below post.

http://social.microsoft.com/Forums/is/crm/thread/1ec656b2-048d-4224-8ff5-ab64e2eaa8f5