The Third Beta on the way to Lightning 4.0

It’s that time of year again, we have a new major release of Lightning on the horizon. About every 42 weeks, Thunderbird prepares for a major release, we follow up with a matching major version. You may know these as Lightning 2.6 or 3.3.In order to avoid disappointments, we do a series of beta releases before a such major release. This is where we need you. Please help out in making Lightning 4.0 a great success.Time flies when you are preparing for releases, so we are already at Thunderbird 38.0b3 and Lightning 4.0b3. The final release will be on May 12th and there will be at least one more beta. Please download these betas and take a moment to go through all the actions you normally do on a daily basis. Create an event, accept an invitation, complete a task. You probably have your own workflow, these are of course just examples.

Here is how to get the builds. If you have found an issue, you can either leave a comment here or file a bug on bugzilla.

You may wonder what is new. I’ve gone through the bugs fixed since 3.3 and found that most issues are backend fixes that won’t be very visible. We do however have a great new feature to save copies of invitations to your calendar. This helps in case you don’t care about replying to the invitation but would still like to see it in your calendar. We also have more general improvements in invitation compatibility, performance and stability and some slight visual enhancements. The full list of changes can be found on bugzilla.

Although its highly unlikely that severe problems will arise, you are encouraged to make a backup before switching to beta. If it comforts you, I am using beta builds for my production profile and I don’t recall there being a time where I lost events or had to start over.

If you have questions or have found a bug, feel free to leave a comment here.


  1. so how would one go about to install this beta version on thunderbird in linux? last i tried, it complained about the version of thunderbird, although it’s the latest from the official mint/ubuntu repositories.

    • Philipp Kewisch

      If you would like to try the betas, you will have to install the latest beta of Thunderbird directly from You can download the tar.bz2, extract it into a directory and try it from there. The ubuntu repositories use the latest stable version of Thunderbird which is Thunderbird 31.

      • so it used to work with thunderbird 38.0bx beta and lightning 4.0bx, but thunderbird 38.0b6 does not seem to be compatible with lightning 4.0b6.

        • Philipp Kewisch

          Please check again with Thunderbird 38.0.1 and Lightning There was an error on Linux with 4.0b6 that has been resolved.

          • Hi there! Ever since agreeing to install the new Thunderbird, the Lightning install won’t work and I can’t see my calendar!! Help!!

          • Philipp Kewisch

            Are you still having this issue with 4.0.1 or

  2. Tested Thunderbird beta 3 with Lightning 4.0b3 and for one user it is running fine while another user’s Internet Explorer started running very slowly going between webpages. After switching back to 31 ESR the issue goes away. I’m thinking there must be a different pref between the two users that is causing the issue. Currently still researching, but figured I’d share in case someone else testing the beta saw this issue.

    • Philipp Kewisch

      I have no idea how Thunderbird could affect Internet Explorer in that way. Let me know if you figure something out!

  3. On Linux with TB 38.0b4 and Lightning 4.0b3, it seems like the dialog for changing calendar color gets stuck when trying to change a calendar’s color.

  4. Just installed the Lightning update to Earlybird, and all my tasks and events have disappeared! How do I get them back?

  5. Sorry, I meant TB Daily.

  6. Oops. I thought it was 4.ob3 because that’s where I wind up when I tried to check the latest version of Lightning. It says 4.3a1 in TB Daily Add-ons.

  7. Seems my previous comments disappeared, so here goes again. Just updated to the latest daily TB and Lightning builds. Now all my tasks have disappeared from Lightning. I can see that they are still there in the sqdb, but not showing in the calendar. Tried everything I can think of . Help!

    • Philipp Kewisch

      Can you check the error console for messages? Also make sure you are using the right version combinations, see

      • This was the latest updates of both. The updates popped up when I started TB Daily, and Lightning after TB checked for compatible addons.
        However, TB Daily is 41.0a1, and Lightning is 4.3a1 which I don’t see either in the list at the site you linked to. So, do I go back to the versions listed at the site, and how would I do that and keep all my setting for TB and Lightning?

        • Philipp Kewisch

          The Daily builds sometimes have issues, yes. Right now there are some issues with binary extensions like Lightning, which can be worked around by setting calendar.icaljs = true in the config editor and restarting.

          To go back to an earlier version, back up your profile and then just start the older Thunderbird on top of it. Lightning will be incompatible because you still have 4.3 installed, then you can use the addons manager to install the older Lightning.

          In case you prefer a slightly more stable build you can move to the aurora builds, or beta.

      • Got lots of calendar error messages in the Error Console. How do I get them to you so you can see them?

  8. I found a bug in Lighting 3.3.3. When the addon is enabled, all my emails (in this case, I only have an Exchange email setup) have empty text bodies. Viewing the source (Ctrl+U) will show all the all the contents there should have been. Disabling the addon, all text bodies can be seen again. I’ve created a bugzilla report link,

  9. installed the updates lightning and TB 38.0.1
    It won’t sync my google calendars until I close and restart TB. Sync button doesn’t do it, taking the accounts offline then back on doesn’t either.


  10. I’ve just done the upgrade to TB 38.01 with the bundled Lightning extension in Windows 10 (final not preview) and found a strange UI bug pertaining to the two icons, “Switch to calendar tab” and “Switch to tasks tab”, that sit in the tab bar next to the “Minimize” button at the upper right of the TB window. When hovering over the “Switch to tasks tab” icon, both the icon and the “Minimize” button are highlighted and the tooltip shows “Minimize”. Clicking on the “Switch to tasks tab” icon at this point minimizes the TB window. This does not occur when the TB window is “windowed”, only when “maximized”.

    Moving the cursor so it’s almost sitting between the two above mentioned calendar icons I’m able to click the “Switch to tasks tab” icon successfully. It appears that TB, when “windowed” still retains the remnants of the old Windows “Title bar” which only appears when TB is not maximized. When TB is not maximized the calendar icons shift down, staying on the tab bar while the “Minimize”, “Maximize”, and “Close buttons” move up into the “Title bar”.

    Note: The “Title bar” is empty of text. Also, Firefox 39 in Windows 10 does not show the remnants of the old title bar at all, “windowed” or not.

    • Philipp Kewisch

      Hi Kirk. Can you try upgrading to 38.1.0 ? Some fixes within Thunderbird have been made that should improve the Theme. If this doesn’t help, can you try disabling Hardware Acceleration? You can do so by going into the Preferences, then Advanced > General > Config Editor. Set gfx.direct2d.disabled and layers.acceleration.disabled to true and restart Thunderbird. If this also doesn’t help please reset those preferences to their default values.

      There is also another issue I recall that should be fixed with one of the next Thunderbird versions.

    • The problem with Thunderbirds title bar (minimize, maximize and close) on Windows 10 is a known issue:

  11. I’ve got a fun TB 38.2 bug re: calendar:
    It’s gone. My calendar tab disappeared. …So did all of the relevant menu items to bring it back, like “show Today pane” “show calendar” etc. (Just doing those from memory, so they’re probably not verbatim what used to be there.)
    There’s also no mention of calendar in the options window.
    The only local proof that I’m not delusional (I swear I used to have a calendar!) is the two dozen calendar entries in about:config. Screenshot of that, here
    The calendar keyboard shortcuts also don’t work.
    …I’ll open a formal bug, but just wanted to comment here, too.

    • I should also note that I’ve already uninstalled and reinstalled TB to no avail.

    • That was quick. I was under the impression that Lightning was now integrated into TB. Poking around a bit, I found that Lightning still exists as an addon. Downloaded 4.0.2 and installed it. Calendar back. Easy. Sorry to hijack your thread. Maybe somebody else will benefit!

  12. Using Thunderbird 38.2.0 on Mac OS X 10.8.5. Started using Lightning about 6 weeks ago when it first appeared bundled with Thunderbird. Found a how-to to add my iCloud calendar by putting together a calDav address at from some information available on my system. Everything works just fine, except one thing: occasionally (I can’t find a clear pattern) that calendar’s properties show the “Switch calendar on” box unticked. So fairly frequently I have to it back on, maybe every other day.

    • This is a known issue and will be fixed as soon as possible ( or 4.0.3). Sorry for the inconvenience!

  13. The calendar does not print full page (landscape) with this update.

  14. Is there a way to stop all my birthdays disappearing every time lightning updates? I put them all in once laboriously with a 15 day advance warning and then they all disappeared. I’m now not sure if it’s worth doing it a again.
    I also wanted to know if there was any way to get my nokia 300 phone to talk to Lightning? Then I could import all my calendar things form there too

  15. I am using TB 38.3.0 to which a security update was applied last week. I have Lightning installed (it auto updated). It is now broken and my View/Calendar menu in TB is disabled. Not the first time a Lightning update has broken my calendar. Tried unnstall/reinstall but no avail. Any ideas?

    I have been using Lightning for 4 years.