Blank startup screen in TB

[required_alias]

Had a popup for a long time when TB was open. Evey few minutes it would popup and prompt me for signin info. Finally got tired of it and uninstalled/reinstalled TB. After that, when opening TB, I get what appears to be TB, but the page/screen? is blank. Solid white with the title bar? gray. That's it. No text. Uninstalled/reinstalled again. Same problem, except, sometimes I don't even get a blank popup. How do I get TB to work?
NOTE: W11 and, yes, I just DLd the most recent TB yesterday.

[DanRaisch]

It sounds like Thunderbird may not be finding a valid existing profile. Try starting it with the "Profile Manager" command line switch and see if you can select your previously existing profile. -- http://kb.mozillazine.org/Command_line_arguments

[required_alias]

Thanks for the reply. I believe that command line is what I need.
However, I'm having one hesitation. when I enter the command line and hit "OK," I get a popup similar to
"A newer version of TB may have made changes to your profile which are no longer compatible with the older version." . . .
I'm running the newest version. What am I missing?

[DanRaisch]

Just so we're clear, what is the exact text you are entering on the command line?

[tanstaafl]

You may have run into the annoying "dedicated profile per installation" feature due to re-installing in a different location. It has a very misleading error message.

Try editing the target field in the properties for the shortcut to add a --allow-downgrade command line argument. Or use the following command line.

"C:\Program Files\Mozilla Thunderbird\thunderbird.exe" --allow-downgrade

[required_alias]

"C:\Program Files\Mozilla Thunderbird\Thunderbird.exe" -Profile "c:\Foldername\Thunderbird"
"C:\Program Files\Mozilla Thunderbird\Thunderbird.exe" -ProfileManager

[tanstaafl]

There is another version of the profile manager available by selecting help -> more troubleshooting information, and clicking on about:profiles . You can then click on the "set as default profile" button underneath the desired profile or experiment with different profiles by clicking on the "launch profile" underneath the desired profile.

Which one you use depends upon your goals.

[required_alias]

Select Help where?

[tanstaafl]

If you press the ALT key that will temporarily enable the menu bar. You can use it to access the help menu. You could also use that opportunity to permanently enable the menu toolbar via view -> toolbars.

If you don't want to do that the widget that looks like a stack of three hamburgers in the upper right corner lets you access the help menu too.

[required_alias]

Making progress. I now have two emails showing in TB.

Interestingly, to me, the folders under each email don't match the folders when I log in to the accounts using a web page.
TB can't 'find' the calendar associated with the email address. Are those profile problems?

[required_alias]

And Message Rules have disappeared.
Are these a function of the Profile. I've tried al of them

[tanstaafl]

Message filters are account specific, and stored in a msgFilterRules.dat file in the accounts "local directory" in the profile.

Calendars aren't account specific. You have to tell Thunderbird what calendars you have.