I just did some testing and some research. Same solution as the same error on Google Chrome.
The problem comes back after a while so developers please do something.
Not sure if its temporary or permanent solution but it worked for me
- Close all Opera GX related processes.
- Go to C:\Users\username\AppData\Roaming\Opera Software\Opera GX Stable.
- Copy and Paste "Webdata" and "Webdata-journal" somewhere and keep it safe.
- Delete "Webdata" and "Webdata-journal".
- See for yourself.
- If it doesn't work, return "Webdata" and "Webdata-journal".
My search engine returned to Google