On 02/14/18 13:06, James wrote:
$ cat .config/mimeapps.list
[Added Associations]
You have....
x-scheme-handler/http=firefox.desktop;mozilla-thunderbird.desktop;userapp-Nightly-FCZ06Y.desktop;
x-scheme-handler/https=firefox.desktop;userapp-Nightly-FCZ06Y.desktop;mozilla-thunderbird.desktop;chromium-browser.desktop;
x-scheme-handler/http=firefox.desktop
x-scheme-handler/https=firefox.desktop
in that file.
try deleting the first 2 and then restart T-Bird and try again.
--
A motto of mine is: When in doubt, try it out