since the update to Quantum widevine does not work where it worked before
On kubuntu -- both 16.04 and 14.04: After the update to Firefox Quantum viewing DRM content (on www.tvnow.at/rtl) no longer works. (Widevine is activated and updated, and I checked the "allow DRM" box).
Alla svar (1)
Not going to like this : uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) or Linux equivalent. Then restart system. Note: your Firefox Profile is saved. But you should make a back up before you do : https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
Reinstall with Current Release Firefox 57.0.2 with a Full Version Installer https://www.mozilla.org/firefox/all/
Please let us know if this solved your issue or if need further assistance.