Seen this? https://support.mozilla.org/en-US/kb/dangerous-directories-Thunderbird-account-settings

Thanks for the suggestion. As far as I can tell, the Dangerous Directories article pertains to where you can RELOCATE A MAILBOX using the ACCOUNT MANAGER; it might well be relevant, though at the moment I can't see how. My problem is upstream of that, having to do with where I can simply CREATE A NEW PROFILE by browsing within the PROFILE MANAGER. I'm having difficulty creating a new profile anywhere else but in the ...cache/thunderbird directory where the default-default and default profiles live, as shown by the the Local fields. I suppose I'm looking for a Dangerous Directories for profiles, analogous to the article on mailbox locations. Or maybe I'm just missing something: entirely possible too. But I suspect a bug, given that failed attempts get handed off to the strange location in the /run directory.

I do not use Linux, I largely gave up due to the inability of the community to approach even simple things in a standard manner. Hence is has been year of Linux on the desktop for more than 25 years. Every year or so I go back a dip my toe and decide they still have not get their act together.

I think I recall hearing that one of the "strengths" or "features" of flatpak is some sort of limitations on where things go and what access you get outside "the sandbox". Here a google search turned up this. https://discussion.fedoraproject.org/t/flatpaks-cant-seem-to-access-most-folders-including-home/76543 It sounds relevant to me.

If you were using the tarball version of Thunderbird from https://www.thunderbird.net/thunderbird/all/ then you would be able to use ProfileManager to create a Profile folder elsewhere besides in the default /home/username/.mozilla/ location for Thunderbird and Firefox.

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-thunderbird-profiles

Note if you can create a Profile elsewhere, select a new or empty folder. If you choose a folder that isn't empty and you later remove the profile and choose the "Delete Files" option, everything inside that folder will be deleted.

Thanks for the suggestions.

I made a TBirdTestFolder directory under my home directory, trying to keep things simple.

I tried creating profiles with that folder having default permissions, expanded permissions (to maximize access), then restricted permissions (in the spirit of Dangerous Directories), but there was no change from what I described in my OP.

I had not mentioned that after Profile Manager writes in the weird /run... directory, if I carry on and click Finish, I get this error message: "Profile couldn’t be created. Probably the chosen folder isn’t writable. [Exception... "Component returned failure code: 0x80520015 (NS_ERROR_FILE_ACCESS_DENIED) [nsIToolkitProfileService.createProfile]" nsresult: "0x80520015 (NS_ERROR_FILE_ACCESS_DENIED)" location: "JS frame :: chrome://mozapps/content/profile/createProfileWizard.js :: onFinish :: line 236" data: no]

This error looks a bit like this unsolved problem discussed here: https://stackoverflow.com/questions/49757241/ns-error-file-access-denied-error-when-firefox-addon-is-installed-the-second-tim

I need to study this, unless someone sees sooner what this signifies.

Another possible fly in the ointment, is that I do have Firefox installed, but I mostly use Brave, and Firefox is usually inactive (closed).

Oh please god let me not have to uninstall the flatpak Thunderbird to replace it with a version from some other repository, hoping to keep emails and profile intact.

Hi there, it sounds like you're hitting a limitation of the default permissions given to the flatpak. Because flatpaks (and snaps) are containerized applications, they don't have access to all the same locations that a typical deb package would have, unless that permission is granted either at build time or by you at runtime.

In Pop_OS and it's Cosmic desktop environment, you can see some high level of the permissions given to each flatpak in the Settings > Applications > Thunderbird. You will notice that there's not much you can do here. If you want a more full featured way of tweaking the permissions of your flatpaks, I recommend installing flatseal - a tool devised to do just that.

`flatpak install flathub com.github.tchx84.Flatseal`

Then you run flatseal and go to Thunderbird and scroll down to the Filesystem section. Here you can try granting the flatpak the permission to access other directories like home or even all directories on the host. Then restart Thunderbird and hopefully this solves your problem.

Matt's reply led me to try to learn enough about github to install flatseal, but Heather's instructions seemed plain enough to try outright.

I ran the automated Flatseal installation to completion, installing for user rather than system.

I closed Thunderbird, opened Flatseal, and gave Thunderbird access to 'All user files'; closed and reopened Flatseal to make sure the setting was permanent. Closed Flatseal. Looked good, I thought.

But when I re-opened Thunderbird via the launcher, it sent me to a configuration window for setting up a new account. With little choice, I set it up. There were NO local folders, which is where all my emails (several years worth) reside.

In the file browser, I found that a new $HOME/.thunderbird directory had been created with 2 new profiles primary 'default-release' and secondary 'default'.

A copy of this same 'default release' had also appeared in the original $HOME/var/app/org.mozilla.Thunderbird/cache/thunderbird profile directory, alongside the original default-default profile. And that profile, formerly with all my archived emails, was reduced to 725 MB, down from 16.3 GB. (I have a copy from last Wednesday).

It seems that Running Flatseal and changing file access caused a reinstallation of Thunderbird that wiped out on-disk mail. Can anyone recommend the best way to restore the original profile from this mess?

Thanks again.