Nextcloud 11 Update blocks login on Linux Mint 19

ā„¹ļø Support šŸ“¦ Appliances (Docker, Snappy, VM, NCP, AIO)
#1

Help! I canā€™t access my calendar anymoreā€¦ or do anything elseā€¦

Now when I go to login (just point my browser to localhost), I canā€™t login anymore, I just get a big button that says ā€œStart Updateā€. Clicking that gives me an error that upgrading between major versions is unsupported. Thereā€™s a link to a help page there, but nothing on that page seems related to what I want to do. Which for now is just to log on.

I have a snap installation of Nextcloud on Linux Mint 19 xfce x64.

I think itā€™s nextcloud version 11 (there are folder names in the snapā€™s nextcloud directory that start with 11xxx, is that right?) and the ā€˜currentā€™ directory is symlinked to 11891.

Is there a way to tell nextcloud that I donā€™t want to upgrade, I just want my old login screen back?

Many Thanks!
Brian