I have the same issue, BTW, I'm using Opera GX and I don't remember the times opera://about/ or opera://update/ worked for me 😃
The other day I was annoyed by this issue again (that Checking for updates… never produces any results), I was on opera://update/ page and noticed Something doesn't work? Let us know here. message. I was happy that Opera upgraded their Bug Reporting service, but upset that after reporting this issue the QA just closed it without any message 😞
Currently to update the browser I'm running OperaGXSetup.exe, which automatically downloads latest version, but it's annoying that I need to manually check if the new version is out. BTW, I subscribed to this thread to get some updates.
Somebody said here that we need to make sure that opera_autoupdate.exe is present in our used version folder, well here's what running this application tells me:
[26824:27312:0924/183827.640:26564421:ERROR:autoupdate_checker.cc(321)] Invalid params.
[26824:27312:0924/183827.640:26564421:ERROR:autoupdate_checker.cc(134)] Unable to prepare update checker runtime.
Anyone understands these errors?