Rated 5 out of 5 stars

by Andy on Feb. 17, 2017 · permalink

If you disable MultiProcess and restart FireFox Save Images addon will work again.
This info was gained from the below support/hack site which goes into much more detail and the risks and how to backup your profile.

ghacks.net/2016/07/22/multi-process-firefox

Check if Multi Processing on by typing
about:support and check the Multiprocess Windows will be set to True

To enable or disable multi-process Firefox, do the following



Type about:config in the browser's address bar.
Confirm that you will be careful.
Search for browser.tabs.remote.autostart.
Double-click on the preference. (it will then set as False)
Setting the value of browser.tabs.remote.autostart to true enables the multi-process architecture in Firefox, setting it to false disables it.
Restart Firefox and you can check that it False by typing
about:support (note it is now False)

Test your Save Files and Bingo!