I am using Firefox 50.1.0 on Ubuntu 16.04. Firefox doesn't seem to be able to download the Widevine CDM needed for Amazon Prime Video, Netflix, etc. On about:addons, the message "Widevine Content Decryption Module provided by Google will be installed shortly." is displayed. On any page with DRM content, the message "Firefox is installing components needed to play the audio or video on this page. Please try again later." is shown in the browser and "addons.productaddons WARN Failed downloading via XHR, status:0, reason: error" is shown in the terminal. I have tried the following: - Toggle off and on "Play DRM content" in Preferences / Content and try again - Change profile - Purge and reinstall Firefox - Using a different network to my usual home network - Copying a working version of the plugin from another computer and manually pasting it in my profile directory I do not have any firewall / anti-virus software running that would block access to anything. For some reason, Widevine CDM works perfectly on my other (Ubuntu 16.04) computer, but not on this one?