I don't want thunderbird to start if a profile (folder) is missing. This works in my "old" thunderbird installation (68.10.0), however on a new machine it automatically creates the missing profile (folder).

My old thunderbird installation behaves like this:

If the profile is not there, it does not start, instead it shows the following message: "Your Thunderbird profile cannot be loaded. It may be missing or inaccessible." And this is the desired behavior.

How can I prevent thunderbird to automatically create the profile folder path and create an new profile if the path is missing?

More precisely: How can I prevent thunderbird to start if the profile is missing?

  • Your Thunderbird profile cannot be loaded. It may be missing or inaccessible. Never seen such an error with any Thunderbird releases even when the thunderbird folder is completely missing: in all cases a default profile has been created automatically. Sep 30, 2020 at 8:29

1 Answer 1


It looks like the change in behaviour is documented here: http://kb.mozillazine.org/Command_line_arguments_-_Thunderbird

Profile Data protection

Some users have multiple installations of Firefox on the same PC. The Firefox developers decided they wanted a dedicated profile per installation to make Firefox more stable when switching installations. This also makes it easier not to worry about backwards compatibility. Since Thunderbird uses the Mozilla Toolkit it inherited this feature in the version 68 beta.

I'm writing this answer as a Firefox user. However, the command-line options should transfer to Thunderbird, since it shares the dependencies as noted above.

New installations of Firefox and Thunderbird (68+, as noted above) come with a 'default' profile. It cannot be deleted as long as it is the only profile available. With that change, the concept of a 'missing' profile no longer applies. There is at least one profile available at any given time. Of course, you can manually corrupt the profile from its directory, in which case Firefox/Thunderbird would display an appropriate message.

There is no direct command-line option to revert to the old behaviour. However, a simple workaround is to use the -ProfileManager argument. This will bring up a Profile Manager window where you can manage your profiles (create/rename/delete). If your desired profile is not displayed, you can directly exit from the Profile Manager window without starting Firefox/Thunderbird.

You can find the full list of profile management arguments here: https://developer.mozilla.org/en-US/docs/Mozilla/Command_Line_Options#User_Profile

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