I ran the mount-spcontentdatabase and it failed. The test-SPContent Database didn't produce anything in the log that would fail the upgrade. Also, the error report didn't have anything that would have failed either? I read that it might be a disk space limit, however, it was turned off. Now when I try to run the Mount-SPConentDatabase it says that I have to run the AssignNewDatabaseID cmd, which is not working. Any advice would be great. Thanks!
Did you check the upgrade status in Central Admin since it provides much more insight into the upgrade process including how long it’s been running, number of errors & warnings, and even what step it’s on in the process? I think url is http://CA/_admin/upgradestatus.aspx . Also try to paste additional ULS logs if possible.
Did you also try to run
Here is the quick summary of upgrade:
Problem will likely due to some customizations. But step 4 will help you eliminate the errors before you run a successful upgrade. Here is the very nice and easy tutorial on how to migrate/upgrade from 2007 to 2010.
Maybe the database id was already available in Config database.
Where this database come from?
If you are adding the database from same server means, first removing the database from Web application properly, and then add the database to web application. Otherwise we may face the error like "AssignNewDatabaseid"