Enter about:support in the address bar and click the Verify integrity button in the Places database section. It should produce a log that you can paste here for an analysis.

Thanks, TyDraniu, for your reply. The following is copy/pasted from Verify Integrity: Places Database: > Task: checkIntegrity - Unable to fix corruption, places.sqlite will be replaced on next startup > 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: 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.

Of course, the corrupt places.sqlite was not fixed yesterday when I rebooted and even shutdown and restarted. Any further help will be greatly appreciated!

Well, what do you know? Firefox seems to have fixed its own glitch without a recent update. I just happened to notice today that I can add new bookmarks. This matter is now resolved, until it comes back up again!

I have the same problem! All my bookmarks disappeared, I can't restore them and I can't add new ones. I followed TyDraniu's suggestion as well and got the exact same log that you posted here. Fingers crossed mine will also be magically fixed!

Update: I copied my profile to a new profile within Firefox and then restored my bookmarks via the bookmark manager, and Huzzah! Bookmarks restored!