Configuration: Unable to upgrade from  TFS 2005 to TFS 2008 when TFS 2005 is working with a SQL 2008 instance.

The scenario is like this:

TFS 2005 was initially installed with a SQL Server 2005 default instance as the data store.

Post installation of TFS 2005 the customer upgrades SQL Server 2005 default instance to SQL Server 2008 default instance.

This causes TFS 2005 servicing to fail.

This also impacts TFS 2005 to TFS 2008 upgrades

 

Why is this unsupported:  SQL Server 2008 is not a supported for DT configuration for TFS 2005.

 

Symptoms you might see: 

Servicing for TFS 2005 fails.

TFS 2005 to TFS 2008 upgrade fails.

 

Remediation Options:

Upgrade TFS 2005 to TFS 2008 using a TFS 2008 + SP1 slipstreamed setup. Instructions to create a slipstreamed setup for TFS 2008 are available in TFS 2008 SP1 install guide: http://www.microsoft.com/downloads/details.aspx?FamilyID=FF12844F-398C-4FE9-8B0D-9E84181D9923&displaylang=en

 

For customer who want to rollback to SQL 2005 to remain in a serviceable TFS 2005 state:

The biggest challenge is SQL 2005 does not recognize the database backups taken from a SQL Server 2008 instance. In simple words we cannot restore a SQL Server 2008 database to a SQL Server 2005 instance. If the customer has recently upgraded their SQL from 2005 to 2008 & if they had taken database backups before a SQL 2005 to 2008 upgrade & they are willing to rollback to a previous database state, they can revert to SQL 2005 configuration as a data store. They can follow the instructions in the restoration based move also called hardware based move to do this task. (http://msdn.microsoft.com/en-us/library/ms404869(VS.80).aspx).

I would advice upgrade TFS 2005 to TFS 2008 instead of rolling back SQL 2008 to SQL 2005.