I've just received an email from Stephen Etheridge (Avast):

Hi there, I am a Product Manager for CCleaner and I'd like to share some information regarding a recent incompatibility between CCleaner and Firefox 79 regarding extension settings storage.

The issue is covered in the following threads:

As I am sure you are aware, this relates to the Firefox 79 change described here.

I wanted to share what information we have about this so that you can help your users avoid issues when using CCleaner. Here's what we know:

Users Affected

  • Use Firefox with a logged-in Firefox account
  • Have ‘Sync’ enabled in Firefox

Behaviour Observed

  • For most Firefox extensions tested, settings data in storage-sync-v2.sqlite-wal and storage-sync-v2.sqlite-shm is wiped but then later restored
  • For NoScript, this data seems to be permanently deleted and not restored
  • We have observed that the v2 syncing process can take some time, depending on the amount of settings data
  • From your forums, it seems it *may* be possible to restore the NS preferences from an old sqlite file, if one exists

Next Steps

  • The CCleaner team is working on a hotfix release as an urgent priority. The fix will prevent CCleaner from removing 'storage-sync-v2.sqlite-wal' and ' storage-sync-v2.sqlite-shm'.
  • We expect to be able to release this very soon (days rather than weeks)

In the interim, below is some info that you can share with your users to prevent CCleaner from removing these files, until we can release a fix.

Temporary Workaround

This workaround is best suited for somewhat technical users. It applies to CCleaner's Custom Clean only (not the Health Check method).

  • If using CCleaner Professional, temporarily disable Smart Clean for Firefox (so CCleaner doesn’t clean Firefox automatically when you close it)
  • Open Firefox and access your extensions
  • Close Firefox
  • Open CCleaner and go to Custom Clean
  • Click on Analyze
  • Double-click on 'Firefox - Internet Cache' (expand the window to see the full pathnames, if needed)
  • Right-click on '...\storage-sync-v2.sqlite-wal'
  • Select 'Add to Exclude list'
  • Right-click on '...\storage-sync-v2.sqlite-shm'
  • Select 'Add to Exclude list'
  • 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 only (Health Check does not read the Exclude list).

Update 2020-08-06

Further email from Stephen Ethereidge:

I'm happy to tell you that we have released a fix for this today in CCleaner v5.70.

CCleaner Professional users will be updated automatically if they have automatic updates enabled. CCleaner Free users can update via the following link:

Download: https://www.ccleaner.com/ccleaner/download/standard

Release Info: https://www.ccleaner.com/knowledge/ccleaner-v5707909

CCleaner Free Installer MD5: 19430f70ccf57837eca389ee422e8882
CCleaner Free Installer SHA-256: 825e7adc69360a9820be17603ec93aace7e998d3278b33b16048d9452f1ba860

Please accept our apologies for any inconvenience caused to your users.

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