Hi nihilistic:
No, this is not a rare occurrence. If you search this CCleaner for Windows board for “Firefox bookmarks” you’ll find several topics from users who had their bookmark and/or other Firefox Profile files (e.g., places.sqlite, favicons.sqlite, etc.) corrupted after upgrading to CCleaner v7.x. For example, see:
- suej’s 03-Sep-2025 Lost bookmarks
- MichaelFum’s 12-Oct-2025 Release version still wipes out Firefox bookmark use
- NicolaB’s 11-Nov-2025 I accidentally cleaned Firefox bookmarks!
- Ben78530’s 22-Nov-2025 Window version 7 Firefox Bookmarks
- Jaap23’s 19-Dec-2025 Firefox distroyed
I would strongly advise you stop using CCleaner to clean you Firefox browser, and just use your Firefox settings at Privacy & Security | History to automatically clear your browsing history each time you exit Firefox - see the Mozilla support article Delete browsing, search and download history on Firefox.
Even better, follow nukecad’s 11-Oct-2025 instructions at How to Roll Back from v7 to v6.39 to downgrade to CCleaner v6.39 and start looking for another disk cleaner to permanently replace CCleaner v7.x - see the discussion in Hmm888’s 30-Dec-2025 How much longer should we stay with version 6.39.
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Dell Inspiron 15 5584 * 64-bit Win 10 Pro v22H2 build 19045.6691 * Firefox v146.0.1 * Microsoft Defender v4.18.25110.6-1.1.25110.1 * Malwarebytes Standard v5.4.6.227-147.0.5453 * Macrium Reflect Free v8.0.7783 * CCleaner Free Portable v6.39.11548 * HDCleaner Portable 64-Bit v2.095