Hi Turbow5, This method recently helped a user with FF 60.0:

Type or paste about:profiles in the address bar Press Enter Look for your Default Profile Next to Root Directory click the Open Folder button Close Firefox

In your Profile Folder find the folder gmp-widevinecdm Move it to your desktop

Start Firefox A new WidevineDRM module will install Go to Add-ons/Plugins and Check For Updates

You can delete the gmp-widevinecdm folder on your desktop.

Cheese! You are awesome. Worked perfectly.

I'm glad I could help.

Browse Safe!

[SOLVED] I rebooted and tried Prime Video, a nice yellow bar came up - which I May have overlooked earlier - saying I need to enable DRM, and providing a button to do so! YAY

________ Details below for how I lost Prime use, for someone else may stumble on this and maybe with .MKV set to always download, Amazon Prime "may" not work I wanted filetype .mkv to auto-download.

I found an addon "Content-Type Fixer" and it fixed my problem - .mkv now defaults to "download"

WELL, that broke Amazon Prime Video - I always get the "Digital Rights Error" and a code of 7235.

1. I disabled the plugin, no diff - the changes had already been made 2. I uninstalled the plugin, no diff 3. I researched thoroughly, mostly finding fixes related to the obsolete ".rdf" file -- I'm on FF V72.. 4. I found "handlers.json" in my profile, and with a hex editor changed the occurrences of "MKV" to "MKX" so there would be no match. - STILL DRM on Prime Video. 5. I closed Firefox, and followed the above steps and moved the folder "gmp-widevinecdm" to my TMP directory. Upon restarting Firefox Still no Prime Video.

By the way, I've never had an extension or plugin named "widevinecdm.." nor could I find it searching for addons! "No results were found for "widevinecdm"."

Any ideas what to do next? Thanks!