If favicons disappear then this usually indicates that there has been a problem with places.sqlite and favicons.sqlite.

Are you possibly using any external software to cleanup files in the profile folder ?

You can check for problems with the places.sqlite and favicons.sqlite files in the Firefox profile folder.

• use "Verify Integrity" button on the "Help -> Troubleshooting Information" (about:support) page

If errors are reported with "Verify Integrity", close and restart Firefox and retry.

Thank you for the reply. What is supposed to happen after I use the "Verify integrity" button? IOW, where do I go or what do I do from there?

You can use "Verify Integrity" to check for issues and possibly do some cleanup. Under normal conditions you shouldn't experience issues with bookmarks and their favicons, so if you get such issues and lose favicons then something else is wrong.

Will backing up one or more of the following files allow me to recover favicons if lost again? If so, which ones?

bookmarks.json bookmarks.html places.sqlite favicons.sqlite

Or is it necessary to backup the whole Profiles folder?

Please excuse my ignorance but, while I have used Firefox for years, I know very little about how its internal workings.

I am also having this problem. I can find no way to contact Firefox.

Hi johnkilcullen30, this site is the official support channel. You have made contact.

Firefox Account said

Will backing up one or more of the following files allow me to recover favicons if lost again? If so, which ones?

• bookmarks.json
• bookmarks.html
• places.sqlite
• favicons.sqlite

The icons themselves are in favicons.sqlite. I don't know how Firefox matches them up with the bookmarks (and history) stored in places.sqlite, so I don't know whether they need to be restored as a pair. That would be a problem because using an old places.sqlite would roll back bookmarks and history as well.

The other two files look like a backup and an export you created at some point. Those won't be useful for restoring/importing icons, but could be useful for restoring/importing bookmarks.

Thanks for the reply. However, I really would like to get a definitive answer to what needs to be backed up in order to restore favicons if lost.

I would assume that backing up the Profiles folder would do it. But if backing up smaller files will also accomplish the task, I would prefer that approach.

favicons.sqlite stores favicons data. In this database there is a moz_pages_w_icons table that stores all the URLs. The moz_icons_to_pages links these URLs to an icon ID and that links to the moz_icons table where all icon data is stored. So it looks that backing up favicons.sqlite is sufficient to backup the favicons.