During a recent restart of our development server the SQL Server started using .NET 4.0 for the SQLCLR. This means that nothing using the CLR in SQL works, or at least that's my understanding by reading these sources:
http://software.intel.com/en-us/blogs/2009/10/16/sql-server-2008-sqlclr-net-framework-version/
www.sqlskills.com/BLOGS/BOBB/post/On-SQL-Server-and-NET-40.aspx
All we get are error messages of this type:
Msg 6517, Level 16, State 1, Line 1 Failed to create AppDomain "xxx.dbo[ddl].3". Method's type signature is not Interop compatible.
Running the statement (as suggested by @john-christensen)
select * from sys.dm_clr_properties
results in the following information:
*Name* *Value*
directory C:\Windows\Microsoft.NET\Framework64\v4.0.30319\
version v4.0.30319
state CLR is initialized
Does anyone know how to solve this or how we can force SQL Server CLR to use an earlier version of the Framework?
Typically you can force a .NET application to use a specific .NET Framework version by specifying the supportedRuntime tag in the application's config file.
So you could try creating a sqlservr.exe.config in the \Binn folder under the root path of the SQL instance and specify there that you would like to use only .NET versions up to 3.5. Check this MSDN link for the structure of the config file.