Resolved. The database was restarted at 09:45 UTC and everything has worked normally since. The cause was a heavy hourly background job; we shipped a fix that cuts its database load by over 95%, and we now monitor the database directly so we hear about problems before you do.

Between 09:18 and 09:45 UTC on October 10 our database stopped responding. Sign-in and the dashboard showed "Account setup could not finish", and agents could not read or save their records. A shorter interruption happened earlier the same day, between 06:33 and 06:46 UTC.