Do you know whether ScreenPrint installs an add-on into Firefox? If so, it's possible that during an update it became disabled. You could check that theory here: orange Firefox button ''or'' classic Tools menu > Add-ons > Extensions category Note that disabled extensions are "grayed out" and listed at the bottom after all the enabled extensions. ---- As far as I know, Firefox does not intercept the PrtScn key for its own purposes, but it's possible that another add-on is doing that. Or if you have interacted with a Flash player in the current page, the player may be intercepting it. ---- If you need a Firefox-specific workaround, you can try this extension: [https://addons.mozilla.org/en-us/firefox/addon/fireshot/ Fireshot].