How do I workaround the Firefox 79 extension cleaning bug?

You might have read recently that as a result of a new storage sync implemented by Mozilla recently in Firefox 79, the current version of CCleaner is clearing setting data in Firefox extensions. Please be assured that are in contact with Mozilla to resolve this as soon as possible (we're aiming for the coming days). In the meantime, here's what you can do to ensure you are not affected:

This issue will affect you if you:

  • Use Firefox with a logged-in Firefox account
  • Have ‘Sync’ enabled in Firefox
  • Clean Firefox with CCleaner (using default settings)

If you are a non-technical user...

Using Custom Clean

  1. In the Firefox cleaning rules section, uncheck ‘Internet Cache’
  2. Click ‘Clean’


  • This avoids the issue but means some files will not be cleaned from Firefox.

Using Health Check

  1. Run Health Check
  2. After analyzing, open the 'Privacy' section
  3. Uncheck ‘Temporary Internet Files’
  4. Return to the analysis results and continue with Health Check


  • Until we have a fix out, this should be done each time you wish to clean Firefox.
  • This avoids the Firefox Extensions issue but means some parts of both Firefox and also other browsers won’t be cleaned.

If you are a somewhat technical user...

  1. In CCleaner Professional, temporarily disable Smart Clean for Firefox (so CCleaner doesn’t clean Firefox automatically when you close it)
  2. Open Firefox and access your extensions
  3. Close Firefox
  4. Open CCleaner and go to Custom Clean
  5. Click on 'Analyze'
  6. Double-click on 'Firefox - Internet Cache' (expand the window to see the full pathnames, if needed)
  7. Right-click on '...\storage-sync-v2.sqlite-wal'
  8. Select 'Add to Exclude list'
  9. Right-click on '...\storage-sync-v2.sqlite-shm'
  10. Select 'Add to Exclude list'
  11. You can re-enable Smart Clean for Firefox if you previously disabled it in Step 1


  • This avoids the issue while still allowing Firefox to be cleaned normally.
  • File exclusions apply to Custom Clean, Smart Clean and Scripted Clean.
  • File exclusions do not work with Health Check (use HC workaround above).

If you are a technical user (INI file user)...

  • See:

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