Today out of nowhere all my events and tasks disappeared from my Thunderbird. However, I have a full backup of .thunderbird folder.

How can I restore my calendar data?

I reverted these files to previous versions:



but I still cannot see any data in my Thunderbird.

What else should I do?

  • Do you use lighting to connect with some online calendar? Which version of Lighting and which version of thunderbird? – danijelc Oct 26 '13 at 9:34
  • @danijelc Only local calendar. Thunderbird 24.0, Lightning 2.6.1 – dev9 Oct 26 '13 at 9:36
  • You probably need TB 24.0.1 version with lighting 2.6.1. There is known bug with your version of TB and lighting check it here downgrade Lightning 2.6 may be solution. – danijelc Oct 26 '13 at 9:54
  • 2
    It's surprising, it worked for me for at least 2 months. I'll try downgrading, but how can I then restore my data? – dev9 Oct 26 '13 at 10:00

Thunderbird data are saved in calendar-data/local.sqlite. In your case lighting 2.6.1 needs thunderbird version 24.0.1., so far thunderbird version in ubuntu is 24.0 and there is compatibility issue between the two versions as already mentioned there is known bug link to Bug #1244619.

Possible fix is downgrading lighting to version 2.6. use this link to download right lighting verision. Since lighting is quite a buggy add-on regular backups of your calendar data could be good practice, especially since you use lighting locally and there is no online calendar to serve as a backup.


I realize that this is an old question, but I was restoring lightning data after an OS crash. This is what I did to get my calendar working:

  1. Close Thunderbird if it's running
  2. Copy all files from backup profile directory's calendar-data subdirectory into your new profile directory. Likely local.sqlite is the only file needed, but I had a few others so I copied them over as well.
  3. Open up prefs.js from your backup and look for lines like:

    user_pref("calendar.list.sortOrder", "3bf851bb-ece1-48df-8de3-c814c05e5fe7");

  4. Open up the same file in your new profile directory and find the same line. If it has a different identifier as its value, replace all occurrences of it with the value from the backup file (there should be 6) and save that file.

  5. Reopen Thunderbird
  • 1
    The most important help were points 3. and 4. witout these you won't see your old calendars if you started from scratch. btw. this did not work for my google subcalendars but that was easy to resolve by readding the account. Still working for Thundebird 45.3.0 – sir_brickalot Oct 2 '16 at 15:23
  • Saved my bacon, still works in tbird 68 – JohnC Nov 19 '19 at 19:53

It seams to be a compatibility problem of thunderbird 24.0.0 with lightening 2.6.1 after a automatic update of the lightening add-on.

You'll find the bug description here: https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/1244619

There seams to be three possible options:

  • How can I "manually upgrade" thunderbird? – dev9 Oct 26 '13 at 10:19

Not neccessary to downgrade right now (20131109). Confirmed that everything is back to normal if you upgrade Thunderbird 24.1.0 (not a typo, I repeat: 24.1.0) from Ubuntu repositories and then upgrade your add-ons from within Thunderbird (Tools/Add-ons and "Check for updates" from the options button next to the add-on search field) or manually by downloading 2.6.2 from here.

(Not a problem with calendar database even when it "dissapeared" or became non-functional while recent Lightning-Thunderbird versions incompatibilities lasted)

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