In case you want details for why this happens, the Adobe Flash Player EOL General Information Page makes it clear the company “ no longer supports Flash Player after December 31, 2020, and blocked Flash content from running in Player beginning January 12, 2021.” In the example below, there should have been a Flash game - instead, all we got was complete and total nothingness. One doesn’t even know that Flash content should have been there. No Flash content is loaded, and no messages about it are shown. If you try to open a Flash website in Firefox, this web browser doesn’t tell you anything about the fact that Flash has been discontinued. What happens if you visit a Flash website in Firefox?

NOTE: This “Firefox enable Flash” tutorial covers Mozilla Firefox version 85 or newer.

Are you still using Adobe Flash Player in Firefox?.

The following versions: 403, 414, 433, 445, 453, and 465 are missing, but all these versions contains the 'kill switch'. You can download version 32.0.0.371 from this archive: For Windows is this file inside the zip: flashplayer32_0r0_371_win.exe And here is the whole Flash old version archive: It's only up to version 387. I'm only using Flash for some work related (safe) websites that are not yet updated for different reasons. People will say that old versions 'will have vulnerabilities by now', but keep in mind, Firefox will ask you every time that a website tries to load Flash content, unless you click on the big red do not enter sign, Flash player will not run.

Latest 'good' version without the killswitch that still works is 32.0.0.371 (released May 12, 2020). The kill switch was introduced with version 32.0.0.387, anything below will still work. There is indeed a kill switch in the 'newer' versions of Flash, even if you have Firefox84 or 78 ESR, you will get an yellow 'f' icon which redirects you to Flash EOL page. Firefox 84 is the latest version that supports Flash, and apparently 78 ESR until Moziilla will kill it.

Firefox flash plugin failed to load