Clear cache for Thunderbird is quite different in its overall affect compared to Firefox, so your result is not surprising.

What version were you using prior to 139? What steps did you use to install 139?

Was a new Thunderbird profile created in the process? In other words, were you prompted to recreate your accounts? (Having a new profile may have resulted in the menu bar not being displayed)

Thank you for your prompt reply.

I have rarely--if ever--undertaken to manually update Thunderbird, other than to verify that a new installation had the latest version. I've always let it do its auto-update thing. I'm not sure what version I had on that fateful day when I opted into the release update channel, which was the day that Mozilla notified me at startup that I had the option.

I was not prompted to recreate my accounts or any such rigamarole. Things just went pear-shaped.

Is there any way I might have unintentionally changed the window layout by unknowingly clicking and holding a mouse button while mousing past the TB window? My fingers don't always stay awake.

> Is there any way I might have unintentionally changed the window layout

Unlikely. You would have had to explicitly done View > Toolbars > and unchecked Menu Bar

However, there was a bug, present in 139.0.1 (not 139.0.2) which resulted in cards view and vertical layout, where the previous setting had been table view and classic layout. AFAIK that did not affect Menu Bar.

As for your first paragraph .. I don't follow.

For example, what is "Trash and Junk; now it no longer delivers email to my Inbox or Trash at startup."? What are the sequence of actions/steps?

Over the years, Thunderbird had gradually developed a pretty good idea of what sorts of emails it should put in my Inbox, Trash and Junk folders at startup and each time it checked for mail. Now it puts all of my new emails in the Junk folder at startup and through the day. I have to repeatedly run the Whitelist filter to get whitelisted email into the Inbox, and i also have to keep adding filters to the Whitelist because all of my email goes into the Junk folder. I have to drag emails that I prefer to have in the Trash folder into the Trash folder. (I use the Trash folder as an intermediate location for emails that I don't always read but wish to keep an eye on--it makes it a lot easier for me to scan them.)

All of my individual filters (720 of them, I think, most of them against spam) and the Whitelist filters (about 30 so far) are set to run manually and when getting new mail.

I have the impression that Thunderbird's ability to learn and remember is getting to be as bad as mise is.

> I have the impression that Thunderbird's ability to learn and remember is getting to be as bad as mise is.

This should not be normal for you, nor the norm in the general population of users.

First, who is your mail provider? Second, do the messages in the Junk folder have the flame icon red, or grey?