Thank you.
Following the instructions int the Widevine + H.264 Support on Ubuntu 19.10 post fixed it for me.

I use the deb version.

Ok I think the problem was somewhat fixed and I don't know why.
I read into the problem a little bit more specifically for Linux and fond that in earlier versions you had to install libu2f-host0. After installing it Opera still crashed. I came back to the problem today and it just worked somhow. I don't know why exactly especially since I restarted Opera multiple times before and after installing libu2f and I don't even know if libu2f was the problem. But somehow it just worked today. Weird.

I have to add a small correction to the sentence: "Authentication with a registered device works without problem." ... I later noticed that logging into Github with a hardware token also crashes.

I use the deb version.

Hello.
I recently got my hands on a YubiKey 5. While using Opera I had 2 issues:

1. I could not register the key on any website (Google, Dropbox, Gitlab, ...) they all had an error:5
2. Using the official Yubico website to test the fido2 or u2f authentication (https://demo.yubico.com/webauthn-technical/registration) while the key is plugged in will simply crash the whole browser. After restart opera noticed it crashed but had no crashlog (automatic crashlog sending is enabled)

Authentication with a registered device works without problem.

I tested it again on Chrome and Firefox and everything worked flawlessly.
I use Opera 65.0.3467.48 on Ubuntu 19.04 (x86_64; with GNOME)

Thank you.
Following the instructions int the Widevine + H.264 Support on Ubuntu 19.10 post fixed it for me.

Hello,
I updated Opera today to version 64.0.3417.92 , but it seems like every video stream is broken. Youtube Live Streams will show "Your browser does not currently recognice any of the video formats available.", Twitch player says "The video download was cancelled. Please try again. (Error #1000)" or sometimes "This video is either unavailable or not supported in this browser. (Error #4000)" and Mixer just loads indefinetly.
Since it worked yesterday I suspect the update. I have already tried clearing cookies and browser cache but nothing seems to work. Disabling extentions also doesn't change anything.
OS: Ubuntu 19.04