If you have sync, and there is a problem anywhere, Shut Down Sync Immediately On All Devices to prevent the problem from spreading. Once the problem is fixed, perform the same repair on all computers/profiles before using sync again.

[v57+] Places Maintenance is built into Firefox.

Type about:support<enter> in the address bar.

You will find Places Database near the bottom. Press the Verify Integrity button.

If any errors are reported, check this link: https://support.mozilla.org/en-US/kb/fix-bookmarks-and-history-will-not-be-functional

The places.sqlite file contains your History and Bookmarks. And it looks like it is corrupted.

Type about:support<enter> in the address bar.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Locate the above file. Then rename or delete it. Restart Firefox. The browser should then create a new place.sqlite and recover your bookmarks from the backup files.

Note: Your history is not backed up and will be lost.

Thank you. The problem only applies to Instagram photos that are bookmarked. They disappear after a few days. All other bookmarks are fine.

Did you do what I posted above?

Diagnose Firefox issues using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

I won't know until after a few days as it is only after a fer days that the Instagram photo bookmarks disappear.

Hi, Please go through the below mentioned link and let me know if it works or not: https://support.mozilla.org/en-US/kb/recover-lost-or-missing-bookmarks

Profile data can be removed or not recorded in several ways;

• 1) Running Firefox in Private Mode (nothing is recorded)
• 2) Privacy settings; (In the address bar, type about:preferences#privacy<enter>)
• 3) Many disk cleaners and anti-virus type programs can remove data from browsers
  Open their settings and have them leave the browsers alone.
• 4) Mal-ware.

Many thanks for replies. Apologies for delay in getting back. I am informed now that the Instagram photos are programmed to expire after a few days when the urls expire. Letters like CDN or CND were mentioned. This would make sense as the problem only affects Instagram bookmarks.

That was very good work. Well Done. Please flag your last post as Solved Problem as this can help others with similar problems.

Thank you for all the help. Thanks, too, to Naheed. Delighted that the matter is now resolved!