In desktop Firefox, open Settings and search for DRM. Turn on Play DRM-controlled content, give Firefox time to download Widevine, and reload the streaming page. If DRM was already on, check Widevine under Extensions and Themes > Plugins.
01Find the DRM switch in Settings
Section linkOpen the Firefox menu and choose Settings. Search for DRM to find Play DRM-controlled content. Mozilla documents the setting under General on some versions and under Media in Tabs and browsing on others. Turn the setting on if you want Firefox to play protected video.
02Check whether Widevine is active
Section linkFrom the Firefox menu, open Extensions and Themes, then Plugins. Find the Widevine Content Decryption Module from Google and choose Always Activate in its menu if it was disabled. If the setting is already on and Firefox still fails to load the module, turn Play DRM-controlled content off and back on to have Firefox reload the DRM components. Then reload the streaming page.
03Compare a protected title with another video
Section linkTry playing an ordinary video and then a protected title. If the error happens on only one streaming site, test with your content blocker paused for that site and then restore its setting. If the error continues, write down the site’s error code and check its Firefox requirements. If ordinary video also fails, use Mozilla’s general audio and video troubleshooting steps.