Hello https://support.mozilla.org/en-US/questions/1542694#answer-1774456 You do not answer the question asked. https://support.mozilla.org/en-US/questions/1543094 What are your actions to try to solve. Have you verified also your security software.

What question was asked? I deleted all of the favicons and places files. Yes, I confirm that I do have security software.

https://support.mozilla.org/en-US/kb/fix-bookmarks-and-history-will-not-be-functional Have you created a new database. https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox <blockquote>Places Database Firefox periodically performs maintenance tasks on your bookmarks and history database (also known as Places database). Use the Verify Integrity button to perform those tasks on-demand. If you're having any problems with bookmarks and history, the Verify Integrity tool might help. </blockquote> Please, Verify Integrity, and post the result. Have you tried start Firefox in Troubleshoot Mode. https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode Choose the option Open.