See https://support.mozilla.org/en-US/questions/1353613#answer-1450213

See https://support.mozilla.org/en-US/questions/1353613#answer-1450213

Yeah, I have read that thread several times, and am unable to make it work on Linux. Am getting same error about prefs.js. Thanks anyway, though. I am missing some other salient point in this.

If you see an error about prefs.js, and don't have a good backup, it's probably faster and easier to try a new profile, with a fresh prefs.js, to see if the issue is in TB or at the OS level. Help/More Troubleshooting, about:profiles, to create and run profiles. Add an account to the new profile and test for crashes. The current profile is unaffected and any profile can be launched from about:profiles.

If it doesn't crash in the new profile, data can be transferred from the old to the new. If crashes remain, it might not be due to a corruption in the old profile, and possibly caused by a font issue in the OS.

So I ran it in troubleshooting mode, and below is what shows in the console. I tried to bold some stuff that looks like important errors. The prefs.js is shown to be in a nonexistent folder, there is no /tmp/tmp-profile folder. Any insight as to how to fix this would be appreciated.

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1668525916819 addons.xpi WARN Checking /usr/lib/thunderbird/distribution/extensions for addons This page is in Quirks Mode. Page layout may be impacted. For Standards Mode use “”. hiddenWindow.html This page is in Quirks Mode. Page layout may be impacted. For Standards Mode use “”. 4 AddonRepository.jsm:97:12 Successfully loaded OpenPGP library librnp.so version 0.16+git20220124.f06439f7.MZLA from /usr/lib/thunderbird/librnp.so RNPLib.jsm:100:15 Found 0 public keys and 0 secret keys (0 protected, 0 unprotected) RNPLib.jsm:301:15 services.settings: Failed to load last_modified.json: TypeError: NetworkError when attempting to fetch resource. Utils.jsm:330 Successfully loaded optional OpenPGP library libgpgme.so.11 from system's standard library locations GPGMELib.jsm:69:13 gpgme version: 1.16.0-unknown GPGMELib.jsm:241:15 Trying to load /usr/lib/thunderbird/libotr.so OTRLib.jsm:64:11 Trying to load libotr.so from system's standard library locations OTRLib.jsm:64:11 Trying to load libotr.so.5 from system's standard library locations OTRLib.jsm:64:11 Trying to load libotr.so from system's standard library locations OTRLib.jsm:64:11 Error: Cannot load required OTR library

   loadExternalOTRLib resource:///modules/OTRLib.jsm:109
   init resource:///modules/OTRLib.jsm:115
   once resource:///modules/OTR.jsm:118
   init resource:///modules/OTR.jsm:139
   init resource:///modules/OTRUI.jsm:256

OTR.jsm:127:15 This page is in Quirks Mode. Page layout may be impacted. For Standards Mode use “”. Troubleshoot.jsm:651:30 WebGL context was lost. 2 Troubleshoot.jsm:713:17 Uncaught TypeError: tab.browser.contentWindow.showTab is not a function

   toImport chrome://messenger/content/mailCore.js:580

mailCore.js:580:39 This page is in Quirks Mode. Page layout may be impacted. For Standards Mode use “”. 2 AddonRepository.jsm:97:12 Uncaught (in promise) DOMException: Could not open the file at /tmp/tmp-profile/prefs.js

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I've no idea why there are OTR errors, which seems to be related to encrypted chat. Also, if the profile is in the default location, I don't know why there is an error about opening prefs.js.

In any case, importing an mbox file doesn't use the Tools/Import command - it's a simple matter of copying the mbox (with no .mbox extension) into Mail/Local Folders in the profile.

OK. Fool here.

It turns out that the account creation process was not completed, for some reason. Once I completed the account creation process, all this stuff started to work. So, note to developers...for keeping fools like me from getting all tangled up in their own foolishness, it might be nice to have something which cautions the user that the account creation process was not completed, rather than throwing these inscrutable errors. This is submitted with best intentions as constructive criticism!