I've the following issue: I've set up a new TFS2017 with new databases. Now I remapped the TFS2017 to our old TFS2015 databases as described here.
When I now try to connect to the TFS2017 in my webbrowser I get the following error:
TF401054: The requested service level property TFS_SERVICE_LEVEL did not match the expected value. Team Foundation Server requires the Dev15.M105.5 service level but the database currently implements Dev14.M102.
Is there a way to manualy upgrade the TFS2015 databases to match the TFS2017? Or is there any way I can fix this? (TFS2017 repair didn't help)
Thanks in advance :)
EDIT:
I solved my problem as described here on MSDN.
First off, that article you linked was for TFS 2008. In general, don't expect that instructions that applied to a version released in 2008 are going to be the same (or even remotely similar) to the instructions for a version released nearly a decade later.
TFS 2008 didn't even have the same database structure as TFS 2010 onward. I don't even know how you followed those instructions for TFS 2015, since they're totally incorrect and reference command line utilities that haven't existed for 7 years.
I hope you have backups of your databases in a known good state; your best bet is going to be to bring back up a working TFS 2015 instance and then follow modern upgrade documentation.
The basic problem is that your team project collection databases have to be upgraded. Pointing TFS 2017 to TFS 2015 project collection databases without putting those databases through the normal process of attaching them (and thus upgrading them) isn't going to work. In a migration-based scenario, this is typically accomplished via the TFS admin console.
You may be able to go to the admin console and attach the databases, but my recommendation would be to bring up a working instance of your TFS 2015 environment and start from scratch.