If a Thunderbird update resulted in Lightning/Calendar not working, you might find your issue and a recommendation how to deal with it listed below. (Seamonkey users may use these instructions, but details might be slightly different.) Some linux distributions like Redhat and Fedora package Lightning with Thunderbird, and users should be able to use the instructions below. But Linux users who installed Lightning by using the distro's package manager may need [[#w Linux package instructions|Linux package instructions]]. Background: Since version 38 the Lightning calendar extension is bundled with Thunderbird, meaning the Lightning extension comes with Thunderbird and you do not need to download the extension. For versions prior to Thunderbird 38 you will want to download the extension from [https://developer.mozilla.org/en-US/docs/Mozilla/Calendar/Calendar_Versions Calendar versions]. =Lightning disappears after a Thunderbird update (release and beta versions)= This may happen if the update of the add-on is stuck. Don't worry about your calendar data, it is left untouched and will be available again if you follow these steps to restore Lightning: # Go to the {menu Advanced} section of Thunderbird [[Template:optionsorpreferences]] and click on {button Config Editor...} # Copy or start typing {pref extensions.installedDistroAddon.{e2fda1a4-762b-4020-b5ad-a41df1933103}} into the search box # When it is listed in the preferences list below, right-click on it and choose {menu Reset} from the context menu - the preference now isn't bold anymore and its value is empty # Close the editor, leave the Thunderbird options, open Thunderbird's add-ons manager and switch to the list of installed extensions # If Lightning is listed there, click on {button Uninstall} to the right of the list item # Restart Thunderbird After Thunderbird has been relaunched, Lightning will be back and you will have access to your calendar data. =Lightning reappears after a Thunderbird update although I opted out (release and beta versions)= If Lightning shows up for you again after a Thunderbird update and you don't want it: # Open Thunderbird's add-ons manager and switch to the list of installed extensions list your installed extensions # Click on the {button Uninstall} to the right of the Lightning list item # Restart Thunderbird This will stop bringing back Lightning after a Thunderbird update. If you change your mind in future, simply follow the instructions to restore a missing Lightning above (while leaving out steps 4 and 5). =Linux package instructions= Some Linux distributions do not bundle Lightning with Thunderbird, Ubuntu for example. To recover calendar functions you will need to reinstall the extension. If you do not see instructions below you will need contact the support of your Linux distribution to get help. Ubuntu: #Open Thunderbird add-ons manager #Delete Lightning extension #Install package: xul-ext-lightning: sudo apt install xul-ext-lightning #Restart Thunderbird and calendar should be there =After a Thunderbird update, the first day of the week in the calendar views is set to Sunday= This is related to a cross update from a bundled version to a version from [https://addons.thunderbird.net ATN] (formerly [https://addons.mozilla.org AMO]) add-ons distribution platform and cannot be avoided technically at the moment. '''Thunderbird 60.0 has a bug at the moment, that makes this issue appear regardless of the previous update channel.''' If you encounter this issue, please reset the first day in a week to your needs: # Open the {menu Calendar} section in Thunderbird [[Template:optionsorpreferences]] and switch to the {menu Views} tab # Select in the {menu Start the week on} dropdown menu whatever is right for you Unfortunately, this might occur again if you run in the same update scenario in the future. If so, please correct the settings as described before. The Lightning and Thunderbird team tries to avoid this by distributing Lightning updates bundled with Thunderbird, for which this is not an issue. =When I use my user profile from a previous Thunderbird version with a newer version of Thunderbird, Lightning is not updated= If you are downloading a newer Thunderbird version instead of waiting for the automatic update or e.g. you want to test something it a beta version and you don't want to setup everything from scratch, you could use a previously used user profile. When doing so, the Lightning version should be updated when starting the Thunderbird with that profile. If it doesn't, then resetting will help - this doesn't affect your calendar data. # Start Thunderbird with the selected user profile # Go to the {menu Advanced} section of Thunderbird [[Template:optionsorpreferences]] and click on {button Config Editor...} # Copy or start typing {pref extensions.installedDistroAddon.{e2fda1a4-762b-4020-b5ad-a41df1933103}} into the search box # When it is listed in the preferences list below, right-click on it and choose {menu Reset} from the context menu - the preference now isn't bold anymore and its value is empty # Restart Thunderbird N.B.: if you do this e.g. for testing a beta version, and you want to continue to use that copy of the [[Profiles - Where Thunderbird stores your messages and other user data|profile]] on a previous version of Thunderbird afterwards, you eventually would have to do the same procedure on that Thunderbird version again. Therefore for beta testing it is recommended to [[Using Multiple Profiles|use a separate (copy of the) user profile]].

If a Thunderbird update resulted in Lightning/Calendar not working, you might find your issue and a recommendation how to deal with it listed below. (Seamonkey users may use these instructions, but details might be slightly different.)

Some linux distributions like Redhat and Fedora package Lightning with Thunderbird, and users should be able to use the instructions below. But Linux users who installed Lightning by using the distro's package manager may need Linux package instructions.

Background: Since version 38 the Lightning calendar extension is bundled with Thunderbird, meaning the Lightning extension comes with Thunderbird and you do not need to download the extension. For versions prior to Thunderbird 38 you will want to download the extension from Calendar versions.

Lightning disappears after a Thunderbird update (release and beta versions)

This may happen if the update of the add-on is stuck. Don't worry about your calendar data, it is left untouched and will be available again if you follow these steps to restore Lightning:

1. Go to the Advanced section of Thunderbird Settings and click on Config Editor...
2. Copy or start typing extensions.installedDistroAddon.{e2fda1a4-762b-4020-b5ad-a41df1933103} into the search box
3. When it is listed in the preferences list below, right-click on it and choose Reset from the context menu - the preference now isn't bold anymore and its value is empty
4. Close the editor, leave the Thunderbird options, open Thunderbird's add-ons manager and switch to the list of installed extensions
5. If Lightning is listed there, click on Uninstall to the right of the list item
6. Restart Thunderbird

After Thunderbird has been relaunched, Lightning will be back and you will have access to your calendar data.

Lightning reappears after a Thunderbird update although I opted out (release and beta versions)

If Lightning shows up for you again after a Thunderbird update and you don't want it:

1. Open Thunderbird's add-ons manager and switch to the list of installed extensions list your installed extensions
2. Click on the Uninstall to the right of the Lightning list item
3. Restart Thunderbird

This will stop bringing back Lightning after a Thunderbird update. If you change your mind in future, simply follow the instructions to restore a missing Lightning above (while leaving out steps 4 and 5).

Linux package instructions

Some Linux distributions do not bundle Lightning with Thunderbird, Ubuntu for example. To recover calendar functions you will need to reinstall the extension. If you do not see instructions below you will need contact the support of your Linux distribution to get help.

Ubuntu:

1. Open Thunderbird add-ons manager
2. Delete Lightning extension
3. Install package: xul-ext-lightning: sudo apt install xul-ext-lightning
4. Restart Thunderbird and calendar should be there

After a Thunderbird update, the first day of the week in the calendar views is set to Sunday

This is related to a cross update from a bundled version to a version from ATN (formerly AMO) add-ons distribution platform and cannot be avoided technically at the moment. Thunderbird 60.0 has a bug at the moment, that makes this issue appear regardless of the previous update channel. If you encounter this issue, please reset the first day in a week to your needs:

1. Open the Calendar section in Thunderbird Settings and switch to the Views tab
2. Select in the Start the week on dropdown menu whatever is right for you

Unfortunately, this might occur again if you run in the same update scenario in the future. If so, please correct the settings as described before. The Lightning and Thunderbird team tries to avoid this by distributing Lightning updates bundled with Thunderbird, for which this is not an issue.

When I use my user profile from a previous Thunderbird version with a newer version of Thunderbird, Lightning is not updated

If you are downloading a newer Thunderbird version instead of waiting for the automatic update or e.g. you want to test something it a beta version and you don't want to setup everything from scratch, you could use a previously used user profile. When doing so, the Lightning version should be updated when starting the Thunderbird with that profile. If it doesn't, then resetting will help - this doesn't affect your calendar data.

1. Start Thunderbird with the selected user profile
2. Go to the Advanced section of Thunderbird Settings and click on Config Editor...
3. Copy or start typing extensions.installedDistroAddon.{e2fda1a4-762b-4020-b5ad-a41df1933103} into the search box
4. When it is listed in the preferences list below, right-click on it and choose Reset from the context menu - the preference now isn't bold anymore and its value is empty
5. Restart Thunderbird

N.B.: if you do this e.g. for testing a beta version, and you want to continue to use that copy of the profile on a previous version of Thunderbird afterwards, you eventually would have to do the same procedure on that Thunderbird version again. Therefore for beta testing it is recommended to use a separate (copy of the) user profile.