Nevermind I just found out I never got the Symantec update.

@Gwen-Dragon That worked, started right up. Thank you. YPS

Thank you! The workaround works! I do have Symantec Endpoint Protection installed, and I think the software updates are managed by my organization so there is not much I can do about it. I tried adding an exception for Vivaldi in the settings for SEP, but it didn't help. I suppose I have to live with this workaround and hope the situation gets fixed. Thanks again! Ann

@gaelle I can confirm that everything's back to normal, than you

FYI I updated Symantec on a laptop with this issue and it's not been fixed for me...

As the originator of this topic, I can now also confirm that version 2.10.1745.26 is working and with the registry workaround removed.

Gute Nachricht: Symantec und Norten haben uns gerade mitgeteilt, dass sie ein neue Update via Symantec LiveUpdate herausgelassen haben, das das Problem für uns beheben sollen. Sie müssen das Update durchführen, um von diesem Fix zu profitieren. Bitte lassen Sie uns wissen, ob es klappt.

@Alexs Super herzlichen Dank! Die Entwickler könnte es schnell lösen und eine kleine Aktualisierung mit der Lösung wurde vor ein Paar Stunden herausgelassen. Vivaldi aktualisieren

Nice to read that users of Norton/Symantec software got updates and Vivaldi starts again without any patches.

@collin-obol Did my advice typing thisisunsafe had helped you?