Additional detail: I've cleared the data cache in the browser and Netflix cookies too. Same problem persists.

More info: I've reset the default user agent in Firefox, and I don't have any plugins that should cause Netflix video to not play. I have 2 ad blockers installed, but both are disabled for Netflix.

Does it still happen with the flatpak package?

You will also need to install the ffmpeg flatpak that matches the Firefox runtime (23.08):

flatpak install org.freedesktop.Platform.ffmpeg-full//23.08

I don't know, I have not tried Flatpak. Why does it not work from the snap package?

Are you able to visit *redirector.gvt1.com*? It should show a 404 error message with a Google logo.

Try changing DNS over HTTPS (DoH) to "Off" or "Max Protection" and in Connection Settings change "Use system proxy settings" to "No proxy".

Checking the "redirector" site you linked I get a 404 as you mentioned.

I turned off DNS over HTTPS and that did not fix the problem.

I do not have any proxy set on the browser or this entire system.

Does it still happen in a new profile? An easy way to test a new profile is to install Developer Edition and see if it happens there or refresh your existing profile. Make sure you stay signed out of your sync account when testing.

I tried Troubleshoot mode and it does not work that way either. Wouldn't that be about the same as using a new profile?

No, Troubleshoot Mode only disables a few settings while a new profile is a clean slate. Installing the flatpak package is another way to test a new profile.

I created a new profile and started Firefox with that profile, same error even though the OpenH264 and Widevine plugins were installed and DRM enabled.

You can check the connection settings and check for possible issues with a Proxy or VPN service.

• Settings -> General -> Network: Connection -> Settings

If you do not need to use a Proxy to connect to internet, select "No Proxy" if "Use the system proxy settings" or one of the others do not work properly.

See also:

• https://support.mozilla.org/en-US/kb/connection-settings-firefox
• https://support.mozilla.org/en-US/kb/websites-dont-load-troubleshoot-and-fix-errors

I mentioned in a previous post that I do not have any proxy configured in the browser or the system in general. No proxy, no VPN, just straight to the Internet via the usual in-house router.

Do DRM protected videos work on other sites like https://bitmovin.com/demos/drm?

Did you try the flatpak package?

I tried the bitmoving site you linked, the video plays.

I also tried this one below clicking on videos that show that they use Windvine, those play too.

https://shaka-player-demo.appspot.com/demo/#audiolang=en-US;textlang=en-US;uilang=en-US;asset=https://storage.googleapis.com/shaka-demo-assets/sintel-widevine/dash.mpd;panel=ALL_CONTENT;build=uncompiled

I have not tried Flatpak. I have Firefox installed via Snap ever since Ubuntu switched the package to Snap. As I mentioned it worked great before I upgraded from v120.x to v124 and 125.

I do not understand why this happened.

Does it still happen with the ESR version (115)?

The ESR version did not work either.

So I went back to FF 125.x. Then I discovered that if I update all snap packages the problem is resolved !

I noticed that ffmpeg was updated via the snap package updates, so that might have been the underlying issue.

I do NOT like the snap subsystem. Apt is much better.

I had the same problem after installed Ubuntu 24.04, but I have fixed installing libavcodec-extra ffmpeg after installing ffmpeg.