Restoring differential backup from SQL Server 2005 to SQL Server 2012 We are migrating a client to a new server. Their old server has SQL Server 2005. I have attempted to perform a differential backup however I received an error about the LSN chain being broken.

Please note I have done this many times, the full backup is restored on the new server with NORECOVERY and then when I go to restore the diff backup I get the error about the broken LSN chain.

I made a test database, got the same result. I then took the test database files and moved them to a server running SQL Server 2008 R2, the backup restored correctly. 

Does anyone know why the differential backups from SQL Server 2005 will not restore properly on SQL Server 2012? And how can I fix this?
There should be no issue restoring differentials and fulls from SQL 2005 to SQL 2012.  I would validate that your backup files are compatible.  To do this, you'll want to use the RESTORE HEADERONLY command and compare the full backup's FirstLSN value with the differential's DifferentialBaseLSN:

restore headeronly
from disk='X:\BackupFiles\foo.bak'




If these values do not match, then you will need to take an appropriate full backup.