Upgraded from 6.1.9 Pro to 6.2.4 Pro now Seahub refuses to start

I recently installed a new server on Ubuntu. I originally installed 6.1.9 using the install all script. This morning I upgraded the server to 6.2.4, now the seafile starts, but seahub will not. It says seafile controller is not running. But if I try to start seafile again, it says it is already running.

I am a complete noob to Seafile, and a relative beginner to Linux, so any and all suggestions are greatly received.

I have taken a look at the various logs, but without knowing what I am looking for, nothing seems to jump out at me.

Did you run the upgrade as root instead of the Seafiles user?
Please check your file/directory permissions. Sounds like a permission error, the pid-file might already exist owned by root or something like

I ran the upgrade as seafile.

But just to be sure, what pid file are you referring to?

If I use chown seafile:seafile for the seafile directory, would that resolve it?

pid files should be located in the folder pids
You might give it a try and set owner of all data to seafile but if you ran the upgrade as the correct user this might not be the issue.

Could you post the output from controller and seahub log files? Just those lines when you try to start it.