SQL 2005 v9.0.2047 (SP1) - The query processor could not produce a query plan

I wanted to post a message here in case anyone else has the same problem I did (as this is the top result in Google).

While upgrading an existing application to use ASP.NET MVC 4 I received the following message: "Internal Query Processor Error: The query processor could not produce a query plan."

Not the clearest explanation in the world... If you are receiving this message while working with Entity Framework, you might want to look at the Compatibility Level of your database.

In my particular case the database was set to SQL Server 2000 compatibility mode and running on SQL Server 2008 R2.

Changing this resolved the issue.