Lightning 1.0b4 Release Candidate 1 is available

The Thunderbird 5 release is just around the corner so its about time to provide a release candidate for the Lightning extension for calendaring. The upcoming version of Lightning will be called 1.0b4 and will be compatible with Thunderbird 5.

Unfortunately, this round of testing will be very very very short. Thunderbird 5 is slated for this Tuesday, the 28th and its critical that we have our release ready for this date. To compensate for the short period, we will be ready to spin another release if something major is broken, so if you are reading this after the release, please do file bugs as quick as possible if you find some.

Candidate builds for Lightning 1.0 beta4 in 36 languages are available as of now for:

A corresponding build of the Provider for Google Calendar is also available at those locations.

Note you will need Thunderbird 5 (or a beta thereof) to try it out. You are encouraged to back up your profile before upgrading. To install these builds in Thunderbird 5, please follow these steps:

  1. Download the build for your operating system to a folder on your hard disk.
    NOTE:Please make sure, that you right-click on the links above and choose “Save Link as…”. Otherwise Firefox will try to install Lightning and you will get an error message like “Lightning 1.0b4 could not be installed because it is not compatible with Firefox.”
  2. Open Thunderbird, then open its add-on manager via Tools –> Add-ons (or the corresponding entry in your language)
  3. Click on the Tools Icon, then select “Install Add-on from File…” and navigate to the lightning.xpi file that you just downloaded.
  4. Restart Thunderbird after the add-on installation has been performed. Voila!

Remember, testing is very important. The earlier errors are found, the faster we can react and possibly post another release on short notice.

Please tell us what you think of these candidate builds and file bugs in Bugzilla as you go. Thank you very much for your support, we couldn’t do it without you!


  1. Hi
    After Thunderbird was upgraded to 3.1.11, lightning (1.0b2) has disappeared.
    I have tried to:
    – deinstall lightning and the hgoogle calendar provider (since I was using it to access my google calendar)
    – enable/disable
    – tried installing v 1.0b4 – which said that it was not compatible with this version of thunderbird
    Any help would be appreciated

  2. Ok, the eagle has landed :)
    One thing that almost immediately came up though was that a couple of users weren’t sure where to get the application in our locale cause the addon page looks like it’s just in English. It might be worthwhile telling users somehow how to get their language. One thing I don’t know for example is if someone using Tb in English could use Lightning in another language.
    Just a thought

  3. I updated today to TB5. Some Add-ons were not avaiable but Lightning and the Provider for Google Calendar were.
    Thank you for your great work!

  4. Pascal Chevrel

    The nightly builds are only generated for mac:
    Any chance to have nightly builds for Thunderbird Nightly as well?

  5. It’s working like a charm! Thank you for making this happen!

  6. Updated my thunderbird to 5.0 and lightning (1.0b4).
    We are using davical ( as server. Until know every thing works as expected. No new bugs so far.
    If everything is working properly I will upgrade the other 10 clients as well.
    Thanks for you work!

  7. Updated my thunderbird to 5.0 and lightning (1.0b4).
    I had problem with locale. What about pt-BR locale? I’m from Brazil and this locale is not present on lightning.
    Any additional download?
    Thanks for all!

  8. Philipp Kewisch

    akerbeltz, I’ll note this in the release notes that I have yet to upload. Thanks for the suggestion!
    Pascal, I’ll start the nightly builds again next week. I turned them off for the release, but mac has a watchdog that keeps restarting it. See for status.
    Laercio, unfortunately pt-BR didn’t translate all strings in time, therefore they weren’t added to the release builds. They had about 90 strings missing. If you would like to help them with translation, please see

  9. I found a problem with Lightning.
    Before, if I put a task with a far start and deadline, I saw this into the todaypanel, in addition to the ongoing and past due.
    Now I can only see if it matches exactly with the same day of the activities!
    it’s a bug or you wanted to introduce it?
    it was convenient to see tasks still to begin..

  10. Most of the bugs I have with Lightning are more than 6 years old, and still unaddressed. That makes beta-testing seem like rather a waste of time.

  11. how can i share it between xp and linux
    in the old version i did it so and it works fine
    but when i do the same in version 1.04 it doesn’t work

  12. Since upgrading to TB5 and Lightning1.0b4, every time I open my calendar, Outlook 2007 jumps in and tries loading all my remote calendars. Very annoying…not sure if Win7 is the culprit here, or if there’s been some change in the way remote calendars (ical on rackspace) are loaded.

  13. Philipp Kewisch

    Drew, known issue. Will be fixed in the next release, upcoming next week. You can work around by changing all your webcal:// calendars to http://

  14. Have installed lightning onto TB5, reasonably successfully. Set to check for updates automatically.
    However, even though it tries to advise me of events (through the reminder pane) the pane itself is completely blank.
    Has it got alzheimer’s?
    (Ie it knows it has to remember something…but isn’t sure what…or when….!)

  15. Philipp Kewisch

    Hi Diana,
    please check out the latest blog entry, we’ve released a new version that fixes this issue.