And for the love of god, can we PLEASE document the fixes we're finding along the way.

I'm currently impacted by the user registration bug that relates to user constraints in the DB - and it's completely ruining what would be an amazing launch. However, apparently some other server owners have it working! Buuuuuttt, no one is posting their secrets - and it's really hampering my ability to deliver this instance.

So, please, someone explain how I fix this issue and get a working instance.

Do I need to roll back? If so, what version? Do I need to run some PSQL? Do I need to patch some Rust?

EDIT: SUCCESS!

Here is the sacred knowledge for my particular situation.

It was half PEBKAC and half bug -

The PEBKAC - If using protonmail SMTP - you'll need 'starttls' for it to work.

If SMTP is broken in this way, it seems to cause a bug in user creation that will essentially create partial data that would prevent user creation with the same name from occuring again. You can use a "plus" address (ie youremail+stuff@domain.com) to work around this in the meantime.