TF30045 is a generic error message. So this is just one of the possible reasons. I restored databases from TFS 2015.2 to TFS 2015.1 so the App tier is not recognize the configuration database.
- Upgrade the App tier to match the data tier. In my case, from Update 1 to Update 2
- Remap the databases (RemapDBs)
- The upgrade wizard won’t work because it’s already the same version
- I have to use /Continue when remap the database and don’t have a sound SSAS setup in my lab for TF400673
- After remap, run the wizard again to finish the upgrade