Please Copy/Paste about:preferences into the Address Bar and then Enter.

Go down the page till find Applications. Default is Always Ask. This way you can view the extension or change it.

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

This did not solve my problem. Images still save without file extensions when dragging and dropping from the browser to my computer. (Note that the problem does not occur when clicking a download link or selecting "save as," but only when dragging and dropping)

uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. 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

Reinstall with Current Release Firefox 57.0 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.

Sorry, to clarify, I am on a Mac, and am running Firefox Quantum 57.0 (64-bit)

This problem only started with the most recent update

I'm having this issue as well (on Mac) and filed it as a bug on Bugzilla a few days ago: https://bugzilla.mozilla.org/show_bug.cgi?id=1419503 And someone else did the same: https://bugzilla.mozilla.org/show_bug.cgi?id=1418073 I don't know if it's actually been worked on, we'll just have to wait and see I guess.

The only workaround I know now is using 'Save image as...' from the contextual menu. In my case other formats like PNG or TIFFS are not affected.

Basicsman said

I'm having this issue as well and filed it as a bug on Bugzilla a few days ago: https://bugzilla.mozilla.org/show_bug.cgi?id=1419503 And someone else did the same: https://bugzilla.mozilla.org/show_bug.cgi?id=1418073 I don't know if it's actually been worked on, we'll just have to wait and see I guess. The only workaround I know now is using 'Save image as...' from the contextual menu. In my case other formats like PNg or TIFFS are not affected.

Thanks! Glad to know it's not just me, I guess. The same applies for me with other file types: SVG and GIF save with the extension as well

https://support.mozilla.org/en-US/questions/1178764 https://support.mozilla.org/en-US/questions/1177461 https://support.mozilla.org/en-US/questions/1189481

seems to be a correlation, I have the same problem too and I don't have this behaviour with Chrome!

This is marked as Fixed in Firefox 58. Switch to the Beta channel if you need it now.