There is a preference "media.gmp-widevinecdm.visible" When it is set to true we can see the Widevine addon in Add-ons and Themes. When Firefox is close the setting reverts to false and the addon is no longer visible. Is this expected behaviour? We cannot get Netflix to play DRM content. We are currently getting the UI3012 error. We updated the prefererence "media.gmp-widevinecdm.force-chromium-update". I don't have a netflix account so I can't test on my PC, but setting the above preference on my PC and visiting netflix.com seems to be enough to trigger the installation of Widevine, as I have a folder called; F:\Users\Tanya\Profiles\ownri05i.default\gmp-widevinecdm\4.10.2891.0 On my PC. My brother, who is the one experiencing the issue, says he does not have the gmp-widevinecdm folder in his profile folder. However, before updating the force update preference he was getting the F7701-1003 error which changed to UI3012 after setting that preference. The problem started when I updated his PC from a very old Windows 10 21H2 patch level (2486), to the current 21H2 patch level 5854 and updated Firefox 115.9.1 to Firefox 128.11.0 Will look into OS version upgrades later in the year, but for now I'd like to get Netflix working again.