Thunderbird 60.0 not starting (+no visible error message)

I have been using Thunderbird mail client for a while now without any problems.
Actually it worked fine until yesterday. Today it won’t start at all but also doesn’t give any visible error message etc.
My web search produced several people with similar thunderbird problems, but the given solutions didn’t work for me:

  • find/delete thunderbird files “lock” or “parentlock” (not found)
  • run thunderbird in “safe mode” using shift or ctrl key (same result as without key pressed)
  • run thunderbird in “safe mode” using command line “thunderbird -safe-mode” (command not found)
    When I tried “flatpak list” and then “flatpak run org.mozilla.Thunderbird/x86_64/stable -safe-mode” I got the expected safe mode window, but clicking on “Continue in safe mode” again resulted in nothing (no error, no thunderbird). Only in terminal window this command produces a warning: “1534275651318 addons.xpi WARN Can’t get modified time of /app/lib/thunderbird/extensions/{972ce4c6-7e08-4474-a285-3208198ce6fd}.xpi”.
    There were a lot of Endless OS/app updates in the last days, maybe including thunderbird!? Is there anything like an update history in Endless OS (like Eventlog Entries in Windows)?

My Installation:
Endless OS 3.4.6, Thunderbird 6.0 (according to app center) / flatpak installation (see attachment).
flatpak-info_thunderbird.txt (719 Bytes)

Any idea?
(By the way: I always have a second tab with the calendar opened in thunderbird, that I never close; maybe this is relevant?)

@VascoEOS This error has already been reported learn more here

Thanks for the hint!
Seems to be exactly the same problem (same output on “flatpak run --verbose org.mozilla.Thunderbird”).
I’m not sure about what “flatpak update --commit=6d772dbdd5ca95dfa70121d1d1cb91c3f4a1501a330c24c5be36a24e16ac7471 org.mozilla.Thunderbird” does.
It shows s.th. like this:

Updating in system:
org.gnome.Platform/x86_64/3.28
org.freedesktop.Platform.VAAPI.Intel/x86_64/1.6
org.freedesktop.Platform.ffmpeg/x86_64/1.6
org.gnome.Platform.Locale/x86_64/3.28
org.mozilla.Thunderbird/x86_64/stable
Is this ok [y/n]:

(I didn’t dare answer “y” …)

  1. Open the application called ‘Terminal’
  2. In this application run the command:

flatpak update --appstream && flatpak update

Accomplished (dozens of updates / including reboot), but unfortunately to no avail (same problem as before) …

This has already been fixed
Update Thunderbird