P: Updating to version 9 but my catalog from version 8.4 is incompatible

Same issue for me, I did manage to roll back to earlier version and open my catalogue, but still can't open it in 9.1

It is not working for me too

Thanks Rikk, just replied.

Joel and Nick, I've contacted you via email for more information. 

Same here, I also couldn't upgrade coming from 8.4 going to 9.0, then going to 9.1 I get the exact same error pointing me to the lock file issue.

So i upgraded to 9.1  but still can't upgrade from 8.4 catalog.  What am i missing??  I wasn't able to upgrade to 9.0 either.  Still using 8.4.1  error points me to the lock file issue.  

Ahhh, nice! That's the way this forum is supposed to work, huh?

Brenda, most people upgrade just fine. Here's information about the process: Why is Lightroom asking to upgrade my catalog and what does it do?

If you need to roll back, here's how: How do I roll back to an earlier Lightroom Classic release?

Cyndi, that might be a different issue. Post a separate thread with a screenshot and we'll help you figure it out.

So I will tell you sometimes it is recognizing my folders in the upgrade when I launch Lightroom and sometimes it is not. I swear it has a mind of its own. For me Mac has changed the way it is handling external drives so the file path is different and lightroom thinks it has moved/missing...you can Locate the files and move them over but that isn't a long term solution when dealing with tons of files.  So I'm just waiting it out.   When this issue first started I was working around off my desktop with new images.  I also just filled up my old drive and bought a new one, I have not had any issues with new work only old.  Also as far as being lost you should have backups of catalogs stored in a folder.