[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.

When done, copy and post the results here.

> Task: checkIntegrity - Unable to check places.sqlite integrity: Error: Error(s) encountered during statement execution: > Task: invalidateCaches - The task queue was cleared by an error in another task. > Task: checkCoherence - The task queue was cleared by an error in another task. > Task: expire - The task queue was cleared by an error in another task. > Task: originFrecencyStats - The task queue was cleared by an error in another task. > Task: vacuum - The task queue was cleared by an error in another task. > Task: stats - The task queue was cleared by an error in another task. > Task: _refreshUI - The task queue was cleared by an error in another task.

Hi david.s.brenchley, I feel some information is missing from your report, but it's hard to say what is going on, other than the places.sqlite database that stores bookmarks and history is probably locked or corrupted.

If you haven't already, please do a normal exit/quit of Firefox and a normal shutdown/restart of your system to free up file locks and complete any deferred updates.

If problem continue, please see the following article: Fix "The bookmarks and history system will not be functional" error message.