• This issue might be resolved by a Firefox upgrade or a security software update. You can either temporarily disable your antivirus programme or tweak your firewall to see if the problem goes away. Contact the programme provider's support site or switch to a different product if your Internet security software is creating the problem.
• To get more troubleshooting information, go to the menu button, choose Help, and then More Troubleshooting Information. This will bring up the Troubleshooting Information tab.
• Click Open Folder next to Profile Folder in the Application Basics section. The folder for your profile will open.
• Select Exit from the Firefox menu. Wait until Firefox has completely shut down before continuing.
• In the Firefox profile folder, find and rename the files places.sqlite to places.sqlite.old and places.sqlite-journal to places.sqlite-journal.old (if it exists).
• To rename a file, right-click it and choose rename from the drop-down menu. After that, append.old to the end of its name.
• After that, reopen Firefox.
• Firefox will establish a fresh locations database when it reopens. Although your browsing history will be lost, Firefox will restore your bookmarks from the most recent backup file.

Read More: How do I fix Firefox from freezing?