This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

FF4 compatible addons keep disabling as they're 'not compatible with FF4'.

  • 3 replies
  • 9 have this problem
  • 15 views
  • Last reply by whoisus

more options

FF4 compatible addons (like adblock plus and downloadhelper) keep disabling and saying they're not compatible with FF4. I then have to reinstall the addon (often the very same version as before), it works again for a random number of days before deciding it's incompatible again. Is there any way to fix this?

FF4 compatible addons (like adblock plus and downloadhelper) keep disabling and saying they're not compatible with FF4. I then have to reinstall the addon (often the very same version as before), it works again for a random number of days before deciding it's incompatible again. Is there any way to fix this?

All Replies (3)

more options

This can be caused if one of the files that stores details of installed extensions is corrupt.

  1. Open your profile folder, for details of how to find it see https://support.mozilla.com/kb/Profiles
  2. Close Firefox
  3. Delete the following files if they exist, extensions.cache, extensions.rdf, extensions.ini and extensions.sqlite
  4. Re-start Firefox, it will then rebuild the list on installed extensions
more options

You may also need to reset the preferences.

more options

That's fixed the problem. Thank you!