Hi, please : uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do :

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Reinstall with Current Release Firefox 61.0.2 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

Please let us know if this solved your issue or if need further assistance.

Nothing. The file extensions still come up blank. Next suggestion?

Two thoughts:

(1) Does it make any difference if you set Windows to show all file extensions?

https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

That might only affect the file name line and not the extensions drop-down...

(2) Does this affect all sites or are only certain sites affected? The reason I ask that is Firefox may be reacting to a particular content-type header sent by the server, and while most servers will do that correctly for common image file extensions, some could be configured oddly.

First off, I want to thank everyone who is offering suggestions! One of them HAS to hit pay dirt!

Unfortunately, jscher2000, it doesn't make a difference if I set windows to show all extensions. Nice try, though! It seems to affect ALL sites - and I've been testing it on Google, which used to show extensions in the box.

I've researched this problem in the forums and there is a great deal of traffic on the subject, but all stopped after it was claimed to have been solved after FF v.58.

Anyone else (PLEASE)???

Try to rename/remove handlers.json and delete mimeTypes.rdf if present in the Firefox profile folder with Firefox closed to reset all file actions to see if that has effect.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Such an issue might also be a problem with the MIME database key in the Windows Registry. You can check specific file extension keys (e.g. .jpg) in the registry with the registry editor.

• HKEY_CLASSES_ROOT\.xxx

You can check a possibly linked MIME type in the MIME Database registry key.

• HKEY_CLASSES_ROOT\MIME\Database\Content Type\

Hey cor-el! YOU DID IT!!! Apparently, under:

HKEY_CLASSES_ROOT\MIME\Database\Content Type\jpeg,

"extension" was set to "jif" ... the moment I modified it to "jpg," it worked!

THANK YOU ALL SO MUCH!!!

You're very welcome and glad that you were able to fix this.

Me, too!  :)