And what version of Thunderbird? Despite suggestions to the contrary, Linux version of Thunderbird are not Thunderbird as released on Thunderbird.net. They are builds usually made by the rrepo and contain sometimes lots of "non default" settings.

For instance most Linux versions have auto update turned off and the user interface for using anything but the distro rep is non existent. Apparently that is how it has to be in the Linux world were every distro is a hero in their own view.

This makes support difficult, as there is no "base" setup. I can't for instance rely on results in Linux Mandriva to comment on your Linux Mint issues. Linux has remained a bit player for a long time and they still all think it will be "soon" to become mainstream, no it will not because they are not working together. First there has to be a "Linux" for the masses not 100 Linux distros to pick from. Android is the clue, one version of Linux for the platform and of course it dominates.

However there are some constants. The profile.ini is the master location for determining where profiles live. The IsRelative in profiles.ini is usually missed by the manual editing fraternity, so they point to a profile as /dev/sdb1/DOCUMENTS/.thunderbird/luw2i6y9.default/ leave the IsRelative to 1 so Thunderbird goes looking for to profile in a sub folder of the folder holding the profiles.ini file.

The profile manager will normally correctly set is relative.

Using the steps in profile manager to create a new profile and point it to the location you have placed your profile data should work 100% of the time. That is a new profile pointing to /dev/sdb1/DOCUMENTS/.thunderbird/luw2i6y9.default/

The version is 1:60.9.0+build1-0ubuntu0.18.04.1.

After following the steps through the Profile Manager I wind up with:

[General] StartWithLastProfile=1

[Profile0] Name=Mint User IsRelative=0 Path=/dev/sdb1/DOCUMENTS/.thunderbird/luw2i6y9.default/

When I launch Thunderbird it faults with:

Your Thunderbird profile cannot be loaded. It may be missing or inaccessible.

)Also tried it with IsRelative=1 with the same result.)

I'm thinking permissions?

is dev\sdb1 mounted?

My original profile is on my primary disk at /barry/.thunderbird/luw2i6y9.default/

A home directory at /barry is very unusual to say the least. Home directories really should reside underneath /home. So typically your's would be /home/barry.

Is that the case?

I copied the entire .thunderbird folder ...

That was a mistake. You should only copy over the actual profile folder luw2i6y9.default, and keep .thunderbird at it's original location. This is where Thunderbird looks for profiles.ini.

... over to my DOCUMENTS folder on a second drive at: /barry/DOCUMENTS/.thunderbird/luw2i6y9.default/ (or: /dev/sdb1/DOCUMENTS/.thunderbird/luw2i6y9.default/)

Your wording is pretty confusing. /dev/sdb1 is a device, not a folder in the file system.

Based on that vague description I'd expect /dev/sdb1 is mounted to /barry/DOCUMENTS.

Is that the case?

I have read, and re-read all of the suggested "help" pages with no success.

I'd suggest you make yourself familiar with Unix file system conventions.

Path=/dev/sdb1/DOCUMENTS/.thunderbird/luw2i6y9.default/

As said before, this isn't a vaild path. /dev/sdb1 is a device, not a folder in the file system. Keep .thunderbird at it's original location. Only copy over the profile folder. Use a valid path in profiles.ini.

1) the original .thunderbird folder is untouched. 2) the drive and partition where the Thunderbird folder was moved is mounted. 3) multiple variations of the file location have been tried in profile.ini, including the one generated by using the file browser in Thunderbird Profile Manager. None work. 4) It's been many weeks since a reboot of the system so I'm going to try that first. (shades of Windows!) 5) If that doesn't fix it I'll remove Thunderbird entirely and install the latest version downloaded from Mozilla.

Success!

1) Uninstalled Thunderbird and deleted the .thunderbird directory on my SSD 2) Downloaded a fresh Thunderbird install from mozilla 3) Launched, then cancelled the "Set up an existing email account" dialog. 4) Shut down Thunderbird 5) Opened profiles.ini from the newly created .thunderbird directory. 6) Deleted the contents and pasted in only

[Profile1] Name=default IsRelative=1 Path=Path=/barry/DOCUMENTS/vh0qkbm2.default Default=1

7) Started Thunderbird. Was now presented with the "Choose User Profile" dialog. 8) Selected to "Create Profile." 9) Used the "Choose Folder" option to navigate to the /barry/DOCUMENTS/vh0qkbm2.default folder. 10) Saved the changes and Started Thunderbird successfully!

I still don't know what the problem was, but it works now, and hopefully this will help other people.

And as always, back up before making changes!