Can you give more detail on what files you cleared and what reason you had to clear these files ? You also do not have these files in the Windows recycle bin, so you can restore them ?

Note that it is always best to move files to a safe location or rename the files instead of deleting them.

All the .sqlite files actually as I've read in reddit. My custom temporary add-on finally works but it costs to have them deleted. I searched for my problem over and over again for 4 hours to find no related answers. I don't know anymore if I should really rely on FireFox for my school works and things I do.

Can you post a link to this reddit article as you may have misunderstood and deleted more then you should have ?

There is usually no need to remove all SQLite databases and I don't think that issues with installing extensions have to do with such databases. A better way to test for issues is by creating a new, clean, profile.

Sorry for the late reply. It's no longer in my Today history. I don't know really anymore. I can only recall someone said "I still have all my history and passwords. It didn't delete any" and something like that. I had this issue a day or two already. It frustrates me. My problems were "Mozilla How to make button for temporary add-on", "Make HTML play sound", "Custom add-on button for Mozilla not working"

See:

• https://extensionworkshop.com/documentation/develop/
• https://extensionworkshop.com/documentation/develop/temporary-installation-in-firefox/

I did visit those websites. I know how to install temporary add-on but the results are good like my temporary add-ons are working after sacrificing my .sqlite files for some reason.

I can't think of a reason for removing SQLite databases like are used to store personal data like bookmark and history unless you cleared the storage folder as well, but I do not know what your extension is doing and what APIs and permissions it uses.

My add-on doesn't use much except it's only a simple html button to play a sound or at least prompt.