I can not start jupyterhub after upgrade to 5.0, I have already run jupyterhub upgrade-db before start it but error message still:
Found database schema version 0eee8c825d24 != 4621fec11365. Backup your database and run jupyterhub upgrade-db to upgrade to the latest schema.
I am using postgresql for jupyterhub, but from db upgrade message, it seems that the upgrade tool works on mySQL 
So hub 5.0 doesn’t support postgresql yet?
jupyterhub upgrade-db
Was something reported from running this command? Was the exit code 0?
Jupyterhub is tested with mysql and postgres, so it is supported.
‘jupyterhub upgrade-db’ command reported some processes when running, I didn’t copy that message, but as I recall it was something like from 0eee8c825d24 to another code and then from that code to 4621fec11365. no error message and no exit code 0.
I ran this command again after jupyterhub failed to start, but then nothing was returned.
Which directory are you in when you run ‘jupyterhub upgrade-db? Which operating system user are you running it as? If you run it again can you paste all of the output?
What was your previous version of JupyterHub?
Is the error message in your original post the entire output of JupyterHub when starting it? If not could you paste everything?
Can you show us your jupyterhub_config.py file?
Please try and give us as much information as possible!