Hello paulb49,

Thank you for posting on Mozilla Support. We value and appreciate you as a user.

As far as I am concerned, I am sorry to say but you have lost your themes but my question to you is, did you uninstall Firefox then installed the new version or did you install the new version on top of the older version ?

Thank You!

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

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

• https://support.mozilla.org/kb/Profiles

New files will be created when required.

See "Corrupt extension files":

• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions
• https://support.mozilla.org/kb/Unable+to+install+add-ons

If you see disabled, not compatible, extensions in "Tools > Add-ons > Extensions" then click the Tools button at the left side of the Search Bar (or click the "Find Updates" button in older Firefox versions) to check if there is a compatibility update available.

If this hasn't helped then also try to delete the addons.sqlite file.

I installed it over the old. I fixed it by uninstalling everything and then installed it again.

I fixed it by uninstalling everything and then installed it again.