I have about ten IMAP mailboxes spread across some five different mail servers, two of which I control. Thunderbird downloaded my mail this morning, and asked for an update. I let it update to 102.6.0, and on restart the two mailboxes attacked to Sendmail / Dovecot servers could no longer retrieve mail. One is reporting "The mail server does not support any of the available authentication methods" (paraphrased, more on that below); the other simply sits and spins forever at "Checking mail server capabilities". Because older versions of TBird do not seem to be available, I downloaded and installed the current beta 109.0b1. This version does not have the "authentication methods" issue, seemingly, but does still sit and spin forever on the other problem mailbox. Because profile format changed between 102 and 109, I cannot backstep to the older version to confirm the error message wording on the first mailbox. Sometimes when I have a "sit and spin" mailbox, it will turn out that there is a certificate problem; hitting "Get Messages" will then bring up the certificate override window, and allowing the override will then make things work. In this case, it does not; if that's the error (which it shouldn't be, that certificate is current) it's not leting me fix it. What are my next steps?