Se: *https://support.mozilla.com/en-US/kb/latest-firefox-issues *https://support.mozilla.com/kb/Add-ons+are+disabled+after+updating+Firefox ---- Try: *http://kb.mozillazine.org/Corrupt_localstore.rdf 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, extensions.rdf) and compatibility.ini in the [[Profiles|Firefox profile folder]] to reset the extensions registry. New files will be created when required. See "Corrupt extension files": * http://kb.mozillazine.org/Unable_to_install_themes_or_extensions * https://support.mozilla.com/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 do a compatibility check or see if there is a compatibility update available.

I found problem.I had to uninstal Youtube Autoreplay plugin and now everything works.Thanks anyway