Lightning 2.6 has been released

I am happy to announce the release of Lightning 2.6, compatible to Thunderbird 24 and Seamonkey 2.21. The release went live on Tuesday, September 17th and is the next major release after Thunderbird 17 and Lightning 1.9. If you are using the Provider for Google Calendar, you will also have to upgrade to version 0.25.

You may have not received the updates automatically because of server side throttling, you can either wait until the update occurs, force checking for updates via the About Thunderbird dialog, or grab them manually:

Before upgrading, be sure to backup your profile so you can restore in case something goes wrong unexpectedly.

The release notes can be found on An important note for users of Google Calendar via CalDAV (not via Provider for Google Calendar): Due to a server side change at Google, you must update the URL of the calendar, as described in this post.

Should you be experiencing any issues, here are some steps that might resolve them:

  • Make sure that you are running Thunderbird 24 or SeaMonkey 2.21.
  • Redownload and install Lightning using the download links above.
  • If you are using the Provider for Google Calendar make sure you upgrade to version 0.25
If you are experiencing issues (Lightning not installing or the calendar not working at all), try removing the Lightning addon and doing a fresh install. Your calendar data will be kept intact, as it is contained in your profile. To be sure, create a profile backup as described above.

If you enjoy this update or want to thank us for the hard work we have done, feel free to leave a review at If you have issues upgrading, please don’t misuse the reviews. Leave a comment here and I’ll try to get back to you soon! If you are sure you have found a bug, you can also search for it on bugzilla or file a new one if it doesn’t yet exist.


  1. You’re doing a great job. thank you.

    Now do you think integrate calendar side by side? to really be better than outlook

  2. Hi and many thanks for doing great job by keeping up Lightning!

    There is an issue I want to report.
    The latest release does not work fine on Solaris 11 x86 platform with Sun Java System Calendar Server (WCAP). I use TB24 and Lightning 2.6.
    I cannot work with my events any more, however tasks work fine.
    I can create/register the new calendar but it does not show me any my or other events.
    Everything is empty. The sync/refresh does not help me to make it work.
    I’m sure this issue exists on Solaris x86 platform (maybe SPARC) since the same combination of TB24 and Lightning 2.6 woks fine on Windows with the same calendar server.

    The fresh installation of TB24 and Lightning 2.6 did not help me to fix the problem.
    There are no plugins, no other extensions, just clean install of TB and Lightning.

    Please be aware of such problem and I hope you can solve it in the next Lightning version.


  3. Can you please revamp Lightning CALDAV implementation to function like Apple iCAL and IOS devices which use a principal collection as the starting point rather than the current implementation that requires a calendar collection as the starting point? It seems most CALDAV services only support the principal collection starting point such as, Wild West Domains,, etc., where Lightning CALDAV does not work. These services only support Apple ICAL or IOS devices so I am stuck using Lightning CALDAV with Google calendar which is currently broken due to Google moving to CALDAV version 2.

    An implementation that requires a principal collection as the starting point allows users to subscribe to one main calendar and select which shared calendars to synchronize as described at

  4. Is there a way for Lightning to synch with GoDaddy CALDAV calendar which only supports ICAL and IOS devices with setup instructions that only provide CALDAV server name and no principal collection point or calendar URL? I will definitely leave five star review if there is some kind of solution or workaround. I desperately want to stop using Google Apps.

  5. I love Lighning’s calendar functionality – though not these days as my calendars are alltogether unavailable…

    Trying to change my multiple calendar’s URIs according to your blog I would suggest:
    Setting up calendars would be easier, if the URI of that calender could be changed. After a calender has been added, I only can delete and add it once again. No way to improve the handling?

    Thanks for your efforts and hopefulle you succeed in making our calendars available soon again.


  6. This is ridiculous. After upgrading to new thunderbird and new calendar, mz google calendar does not sync. I found out that I probably need to change location of the calendar in the Thunderbird.

    It is not possible! The line where calendar location cannot be edited. A see cursor there but I can not write nor delete a single character. What kind of ridiculous program is that? Omg.

  7. Hello,
    first of all, thank you for providing the tool i most work with!

    In Ubuntu, there is now a bug, when getting notifications. they are always in front of TB. Plus details are behind the notifications list.

    Bug is reported here:


  8. After upgrading thunderbird to 24.0 and lightning to 2.6 I have no mail folders in the left hand pane. Have no idea where they went, or how to get them back, the pane is just empty.

    Fedora Linux 19

    I tested this with a brand new basically empty profile. Updated thunderbird, moved my previous .thunderbird file to a backup, started thunderbird and reset my account settings for my imap mail server. Started thunderbird and everything seemed fine. Installed lightning 2.6 from a downloaded xpi file, the add-on manager couldn’t find lightning and after the restart I have no message folders. Tried resetting views, no luck. Looked at folder subscriptions and it’s empty, no folder listed to subscribe. Tried to remove the imap account and then re-add, but nothing happens when I select “Add Mail Account…”.

    If I blow away the profile, start fresh it all works great, right up until I try to get Lightning installed. Then it all goes wonky.

  9. After updating to Thunderbird 24.0.1/Lightning 2.6 the calendar doesn’t work anymore. Here a screenshot: The calendar tab doesn’t have name, the toolbar is duplicated, no event displayed, can create new event (grey). I try remove/reinstall but it doesn’t help.

    • Exactly the same problem here … this is extremely frustrating and a big nuisance! How can you rely on a software for your appointments if it is possible that it breaks so epically?

  10. Upgraded to 2.6. All of my events in my calendar are now gone and Thunderbird no longer recognizes invitations.

    Complete failure.

  11. I’m having an issue with Lightning after the thunderbird 24 update. I can’t add new calendars, or delete old ones. The drop down boxes for timezone and starting hours are compressed and the timezone setting box does not display anything.

    Thunderbird seems to be working, its just the calendaring that’s shot. There’s no month grid displayed. The add – new – calendar is grayed out, etc.

    All of this used to be running with Thunderbird – lightning, and the exchange calendaring add on. After the Thunderbird 24 update, I got errors about the exchange calendar and I started removing add ins and have already removed an reinstalled lightning numerous times.

    The is all running on Red Hat Enterprise Linux Workstation release 6.3 (Santiago)

  12. Hi, for some reason Thunderbird only updated just now, but unfortunately lightning is broken for me. The error console shows a lot of these, which go away if I disable Lightning. I’ve already uninstalled it, restarted, installed and restarted again, to no avail:

    Error: Components.classes[cid] is undefined
    Source File: resource://calendar/modules/calUtils.jsm -> file:///home/stefan/.thunderbird/sm69za64.default/extensions/%7Be2fda1a4-762b-4020-b5ad-a41df1933103%7D/calendar-js/calUtils.js
    Line: 22

    It seems similar bugs have been fixed (e.g. 882334) but I have no idea how to build Lightning and see if I’m affected by this. I’m on Linux. Any hints would be greatly appreciated.

  13. Thanks for providing Lightning!

    Today I upgraded to 2.6 while doing the TB upgrade to 24.0.1, on Debian Wheezy, using the auto-updater from TB.

    The situation is similar to #1, everything is blank, no events visible (not even in the sidebar), Lightning is not usable for me anymore.

    In the calendar settings for the timezone, the dropdown menu shows nothing. No text.

    If I can help you track down this bug, please respond via mail.


  14. Seems like there is a severe issue with linux: :(

  15. I had the Sunbird, which I’d rather have, but it’s not being upgraded anymore.

    So I added Lightning to Seamonkey.

    When I went to restart, it didn’t show up. When I clicked on “options” in the add-on window, it hung up Seamonkey. Well, I spent hours trying different things to do. Finally, I was thinking Thunderbird is a email program. So I tried to start Seamonkey email and newsgroups, then Lightning showed up. But the “options” in the add-ons still hangs up the browser window.

    What you got to do is start the Seamonkey mail and newsgroups, then use that tools, add-ons, then the browser window opens for add-ons. Add on the Lightning, or enable the Lightning, but don’t use the “restart now” option. Close all Seamonkey windows and start Seamonkey Mail and Newsgroups manually to restart. Then it works.

  16. I was forced to upgrade Lightning today to v. 2.6), to go with a new version of Thunderbird (v. 24.0.1) . All my google calendars stopped working since then. Upon starting Thunderbird, it keeps asking for passwords to my google calendard and does not use them or store them – the request for password keeps popping up. I checked the passwords in web interface and they are correct…

    This upgrade is a complete failure…

    • Gilberto Orozco

      George, same thing happened to me since upgrading to Thunderbird 24 and also with 24.0.1. I upgraded today to Lightning 2.6.1 + Google Provider 0.25 and everything returned to normal.

    • Hi George, I did done system update, but my TB is still 24.0 and latest lightning.. all of the sudden it does not work any more. That is ubuntu 12.04 where updates usually broke things apart. On my debian box where I have TB 24.0 with same add on version works superb.

  17. I upgraded to Thunderbird 24.0.1 and lost my calendar. Went to your site, downloaded the new Lightening release and I am back in business!!

    Thank you so much for all the work you do! Is there a donations page? I really like to donate when I like something and I love Thunderbird and Lightning!
    Again, thanks so much and keep up the excellent work!

  18. Lightning stopped working, no events shown, nothing can be entered or changed anymore. This is really annoying and frustrating.

  19. I lost the old lightning a few days ago, and was told to download the new one. I’m running Thunderbird 24.0.1 on windows 7. I cannot get Lightning to appear! Starting from Add-ons Manager, I click on “Lightning”, which takes me to “Lightning 2.6”, where I click “Add to Thunderbird”. I then click on “Install now” in the dialog box, and a restart bar appears at the top. I click on “Restart now”, and when it re-opens, I am back to the beginning in Add-ons Manager. I have been round this loop several times, and even switched the computer off and on, but still no progress. I’ve also tried switching off the firewall, but this makes no difference. Please help, as I’m lost without my calendar!

    • Philipp Kewisch

      Can you uninstall Lightning, or does it just re-appear every time? I’ve answered another comment recently, the trick is to remove all traces of the Lightning extension manually, then reinstall it. This is a bug we cannot really influence, its in the Mozilla Platform.

  20. Lightning is a pain in the a**, updated Thunderbird, no update for lightning. Cannot delete calendars, cannot change calendar location…

    • Philipp Kewisch

      If you are on Linux, this is the error described in a later blog post. In any case make sure you are using matching versions:

      Thunderbird 24 -> Lightning 2.6
      Thunderbird 24.0.1 -> Lightning 2.6.1
      Thunderbird 17.* -> Lightning 1.9.1

      • Many Many Many thanks.

        I removed the 2.6.1 addon for lightning and installed the 2.6 version from Synaptic to match the 24.0 version of Thunderbird and everything came back!!!
        fwiw; I have now disabled automatic updating of addons.

        (I am running Linux Mint)

  21. We have been using Thunderbird with Lightning with Zarafa as the Caldav server. Since the upgrade to 2.6 lightning does a nice DOS attack on our Zarafa Caldav gateway.
    For every calendar in Lightning there is one Caldav instance running on full speed (whatever the database can serve), looping forever.
    2 Lightnings with 5 calendars each do result in a 8-10 load on the server.
    Before the upgrade the load was not visible.

  22. I am afraid I have had to move to another free e-mail client that can handle Google calendars effectively. I waited patiently for your version 2.6.1 to get around the problems posed by Google but when it arrived, while it worked to a point on my high performance Win7 desktop, one notebook was reduced to a crawl when Thunderbird and Lightning were working in the background, and another froze altogether. Task manager only reported 50% processor activity and spare memory available so I don’t know what was going on. What I do know is that when Lightning was disabled both notebooks behaved as though they had had a major upgrade compared to how they worked even before the problems started. This new turn of speed has been maintained with the alternative software. While I miss some of the options I used to have, it will take a lot of improvement before I return to Lightning.

  23. Same problem on XP, Tbird upgraded to 24.0 + Lightning 2.6 , now I can’t accept
    invitations – tried removing/re-installing Tbird no luck.
    Could you provide a clear solution, I guess many people are now stuck like this,
    we need a solution/fix asap, can I have a refund :)



  24. Thunderbird 24.0.1 doesn’t play well with Lightning 2.6.1, hence the need to get back to 2.6.

  25. Sorry my mistake and you might just not publish the above info. I misread versionnumbers: 24.0-1 and not 24.0.1.

  26. I have several calendars in my Lightning… I also have Provider installed. I’d like to sync all of my calendars to my google calendar, but it’s only syncing one. When I go into the calendar properties of the ones that don’t sync, it has the location as storage, but it won’t let me change the data in that field so I can put my Google URL in there. User “Core” also pointed this out, above. How can I change that field when it doesn’t let me? Thanks.

  27. Still not working for me. Updated to TB 24.0.1 and Lightning 2.6.1 (on Windows 8), updated the calendars to the new Google CalDAV endpoint, but still no go (empty calendar with an error). Looking at the error console, the first error message is:
    [JavaScript Warning: “CalDAV: Unexpected response, status: HTTP/1.1 507 Insufficient Storage, href: /caldav/v2/”]

    What gives?

  28. Have you tried to find “Lightning 2.6” so your can calendar fixed. You would think that Mozilla would keep it in its collection until the main problem got solved. Hello out there please put Lightning 2.6 back in the Add-ons.

    Ubuntu does not have the Thunderbird 24.0.1 on my Synaptic. Somehow I got the update Lightning 2.6.1 with my Thunderbird 24. Guess what Synaptic does not have old Thunderbird Plug-Ins. (So up grade to Thunderbird 24.0.1 – I am terminal illiterate and do not know how to do this.) Where is the Deb file for Ubuntu 14 or LinuxMint 15.

    I just guess here, That all the great people who work on this project use only windows since they did not catch this problem early on.

  29. For those looking for other versions of Lightning here is the link.

  30. Linux Mint 13 (based on Ubuntu 12.04 LTS) 64 bit
    TB 24.0
    Lighthing 2.6.1

    Lost calendar and tasks after automatic upgrade. I looked at the error console and installed xul-ext-calendar-timezones xul-ext-gdata-provider xul-ext-lightning assuming the new version of Lightning might depend on these. Made no difference. Removed those packages again, then removed Lightning 2.6.1 and installed Lightning 2.6.

    A notification from my calendar popped up on my screen so I was hopeful that resolved the problem. Unfortunately, Calendar and Tasks in the View menu are now grayed out.

    It would be good to know how this could mess up so badly and what the developers are doing to prevent this in the future (basic version testing is not difficult, ie. if the versions need to match so exactly, why doesn’t Lightning 2.6.1 not tell me it’s not compatible with TB 24.0??). It’s clearly having quite an impact. It would be a shame if we can’t trust TB/Lightning to handle the data we rely on for our day-to-day stuff with care.

    Meanwhile I’m still stuck without Calendar and Tasks on TB24.0 with Lightning 2.6.
    I’ve removed and install Lightning 2.6 twice now, I don’t think doing it more often will make much of a difference. The directory in extensions where Lightning lives was removed after I removed the addon from TB. If there could be other artifacts remaining, would one of the developers please be so kind to outline exactly which files I should look at?

    • Philipp Kewisch

      I will do a followup post to explain why it happened and why basic version testing didn’t find the issue. Your calendar data is not lost, as long as you don’t remove it from your profile.

      Could you try not using the distribution packages, but instead those from This often makes quite a difference.

  31. Google Calendar sync works for a couple of days since I upgraded to TB 24.1 and Lightning 2.6.2 on Windows. Unfortunately it fails again now. Tried delete the calendar and added back, as usual it prompted for permission from Google which I supposed was fine but truth is it does not work now. Real piss off I have relied on this TB+Lightning for the past few years what I realized it is as terrible as Google Map on my android phone :(

  32. First of all, thanks for this extension (which is in its rights the most important piece of TB after TB itself…).

    Then a little suggestion: in the “More” page from the Extension menu of TB, the homepage link is broken. It is which gives a 404 not found clicking on it. I suggest to change this link with this blog page, being the first one that the user will click when searching for help.


  33. I’m using 24.0 in Linux (PCLinux OS). The T-Bird auto update loaded Lightning 2.6.1 on 10/25/13 & I lost all functions in the calendar.

    I just unchecked the auto update, downloaded & installed the 2.6 version & my calendar is now working again. There was no need to uninstall version 2.6.1.

    It kinda sucks that I cannot use auto-update anymore, I never think to go looking for newer versions of add-ons…..

  34. 2.6.1 seems to be unavailable at
    Where can we get the XPI file for repackaging? (I maintain the ArchLinux package).

  35. Thanks for the update and all the good work! Only issue I had this time was the calendar data missing but reinstall of Lightning fixed it.
    Keep up the good work!

  36. Just updated to Thunderbird 24.1.1 and Lightning 2.6.2 stopped working again :-/

    It is the same issue I had before while jumping through the 24.x.x revisions.

    • Same here Leonardo: Thunderbird 24.1.1 and Lightning 2.6.2 stopped working again… for how it has to go on? Everytime one component gets upgraded calendar stops working…

  37. Killian Gobin-Gallon

    Same as Leonardo, I just updated to Thunderbird 24.1.1 and Lightning 2.6.2 stopped working. And impossible to update to Lightning 2.6.3 in the application.

  38. Giulivo Navigante

    Yeah upgrading to TB 24.1.1 and L 2.6.2 broke things again for me too.

    • Philipp Kewisch

      Also, please check the error console after a restart and let me know what the messages are. Thanks!

  39. Thanks for fixing this issue so quickly (once more time)! :)

    • OK Updated to Lightining 2.6.3, Thunderbird 24.1.1 and Google Calendar 0.25 and it works again. Thank you!!

  40. Ubuntu user here! Thunderbird updated to 24.1.1 and I have Lightning 2.6.3 but it doesn’t work. The “View > Calendar” menu item is greyed out. Any advice?

    • Philipp Kewisch

      Could you check the beginning of your error console after a restart? Looking for messages of files not being able to load.

  41. Multi day events do not work on Thunderbird 24.1.1. Lightning 2.6.3, Provider for Google Calendars 0.25. I am running Windows 7 Home Premium.

    Create a new event. Set the start date and time. Go and set a new end date (different from Start date) and the start date will change to match the end date.

    • Philipp Kewisch

      Ah, try clicking on the chain icon next to the boxes. This breaks/sets a link between start and end date.

  42. I love your product and use it heavily, but today did something that baffles me.
    I have several calendars: 2 from Google, one in Lightning’s default location, and 2 on our LAN.

    After creating the 2 on the LAN, I can now see all appointments, from all calendars, in Day, Week, and Multiweek grid views, but nothing at all in Month view.

    Any clue as to what is happening?
    I’m running Thunderbird 24.2.0 with Lightning 2.6.4 on a Windows 8 machine, with the 2 LAN calendars on a Window Server 2003 machine.

  43. TB: 24.2.0
    Provider: 0.25
    Lightning: 2.6.4

    “There is no writable calendars…”

    What should I do?

  44. Thank-you so much for the hard work, great results for this project.

    I have struggled with getting a single mail/calendar app for my multiple client projects and personal email/calendar all in one place.
    I’ve tried so many different configurations on my OSX device but since all three of Apple, Google and Microsoft are changing their synchronizations services, none of their products work well with the other servers. – at least for my

    I needed to access the mail and calendar on the following: (and they all work!)
    Gmail (personal)
    Google Mail (a client using google apps for mail/calendar)
    Office 365 exchange (a client using this service)
    Exchange server 2003 (yes very old, but able to use it with IMAP for email)

    For those wondering, I’m using the following add ons:

    Using Thunderbird 24.4.0
    Lightning 2.6.4
    Provider for Google Calendar 0.25
    Google Contacts 0.7.12
    Exquilla for Microsoft Exchange 24.6 (only for exchange servers newer than 2004)
    Calendar EWS Provider 3.2.0-Beta52

    Now, off to make a donation!

  45. He arrived in a white Bentley and partied together promoter Alex Gidewon plus V103 Kenny Burns.