Since the Thunderbird application and Thunderbird user data are stored in different, separate directories uninstalling and reinstalling the Thunderbird application won't change anything in your Thunderbird data, also called the Thunderbird "profile". But most times the uninstall/reinstall action of the Thunderbird application won't resolve a problem, since in the vast majority of problems the cause is originated in the Thunderbird profile. Does your issue persist if you start Thunderbird in 'troubleshoot mode'? https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird

It will not start in troubleshoot mode. I am on an M2 MacBook Air running Taho 26.3 (25D125) if that helps. It just started acting up last night, no updates made that I know of. Can I adjust the profile to get it to start up?

It will not start in troubleshoot mode.

Are you sure? I didn't know that you are running a macOS Thunderbird version. So please try again the following sequence: hold down the Alt (Option) key while launching Thunderbird by a left mouse click on the Thunderbird symbol in the Dock, then release the Alt key.

It did bring up the troubleshoot mode dialogue box but still just freezes upon starting. never fully opens.

Do any of the following match or help?

• https://bugzilla.mozilla.org/show_bug.cgi?id=1662759#c28 hangs high memory about 2 seconds after startup while reading from the Mac system address-book
• Bug 1831673 - TB 113 very slow (3 minutes) startup on Mac. (macOS contacts)
• Bug 1817689 Bug 1817689 - Thunderbird hangs on startup in troubleshoot mode when "Settings" are displayed in a tab

FYI https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data describes profiles.

Nothing there seemed to help I'll keep working at it. I have no idea what caused it and now I hoping I don't have to start from the beginning with it.

I cannot find a Thunderbird folder anywhere to see what I want to do about saving previous emails and login credentials. At a loss on what to do next.

Try to create a new profile via the Thunderbird profile manager: Go to Applications > Utilities > Terminal.app Copy/paste the following command line

/Applications/Thunderbird.app/Contents/MacOS/thunderbird -P

in the Terminal window and hit Enter. This will open the Thunderbird profile manager window (image). Create a new test profile, start Thunderbird and set up just one account. Does Thunderbird still freeze?

I cannot find a Thunderbird folder anywhere to see what I want to do about saving previous emails and login credentials. At a loss on what to do next.

At this very moment it is not urgent to seek for the Thunderbird folder in your user library which contains your saved logins, accounts, folders and messages. First we need to know why your Thunderbird installation freezes... The user library in the Finder is hidden by default: to unhide it open a Finder window, press the Alt (option) key and in the Go menu click on "Library"

Do any of the following match or help?

• Bug 1817689 Bug 1817689 - Thunderbird hangs on startup in troubleshoot mode when "Settings" are displayed in a tab

I can no longer reproduce this bug in my Thunderbird 148 profile. Yet it still happens in my 140.8.0esr profile ....

Now I'm setting everything up from the beginning. Is there a setting for the classic look?

Now I'm setting everything up from the beginning.

Did you create a new profile in which Thunderbird is no longer freezing?

Is there a setting for the classic look? </blockquote> Go to View > Layout > ✔ Classic View If you prefer the "Table View" instead of the default "Cards View" > click on the "Message list display options" button (image) in the upper right angle and select Table View in the drop-down menu