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I cannot install any addon that requires a restart.

  • 2 replies
  • 3 have this problem
  • 10 views
  • Last reply by richjmoney

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Firefox 42 on Windows 7

I am able to install any addon that does NOT require a restart, but anything that does simply does not get installed. I do not get any warning message, the addon simply does not install after the restart. To be clear, when I click install it: downloads the file, goes through the installation dialogue, prompts saying it will be installed on restart, and whether I select restart now or I manually restart, it does not appear installed afterwards.

I have done the following things to try and fix this: Started as admin, installed, manually closed, restarted as admin. Tried to manually install the addon. Uninstalled firefox and resintalled firefox. Ensured that my date an time settings were correct. Cleared my extension files from my profile folder. Started my browser in safe mode (I am not prompted to restart however the addon does not actually install).

Firefox 42 on Windows 7 I am able to install any addon that does NOT require a restart, but anything that does simply does not get installed. I do not get any warning message, the addon simply does not install after the restart. To be clear, when I click install it: downloads the file, goes through the installation dialogue, prompts saying it will be installed on restart, and whether I select restart now or I manually restart, it does not appear installed afterwards. I have done the following things to try and fix this: Started as admin, installed, manually closed, restarted as admin. Tried to manually install the addon. Uninstalled firefox and resintalled firefox. Ensured that my date an time settings were correct. Cleared my extension files from my profile folder. Started my browser in safe mode (I am not prompted to restart however the addon does not actually install).

Modified by richjmoney

All Replies (2)

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Try these in order

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options)
key, and then starting Firefox. Is the problem still there?


It is possible that there is a problem with the file(s) that store the extensions registry.

Delete the extensions.* files (e.g. extensions.json, extensions.sqlite, extensions.ini) and compatibility.ini in the Firefox profile folder to reset the extensions registry.

New files will be created when required.

See "Corrupt extension files":

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I attempted to clear my extension files already and started in safe mode, as mentioned in my post. I went through the entire unable to install addons support documentation as well as several 3rd party suggestions. Posting here was a last attempt after attempting to find any solution.


However I was able to workaround my issue, by deleting my extension files (extension.* in my profile folder), manually dropping the .xpi file into my profiles/x.default/extensions folder and going through the dialogue there.

Installing addons that required a restart still doesn't work properly but this workaround seems to handle it.

Modified by richjmoney