Thanks for reporting!

Again, thanks to you and anyone looking into it. Really appreciate.
And sorry if i used a disrespectful tone, as have been pointed out.

For Opera 118 and newer, I couldn't get things to work. Spoofing as Chrome or Firefox didn't help and the --disable-extensions command-line switch (to kill Opera's built-in extensions) didn't help. I also didn't see any flags at the URL opera://flags that would make a difference. It's just broken. With that said though, I can't tell if the Keepa issue specifically is actually a bug with the Web Notification API support in opera or if it's a bugs with the handling of some other Javascript code on the Keepa site. Either way, since it works in 117 - 102 for example, I'll file a bug specifically for the Keepa issue to see if someone can figure out the cause and hopefully, that might fix other notification issues.

On a side note, in testing some builds from 102 - 114, I noticed that sometimes notifications would stop working for Keepa in Opera. To make them work for Opera again, I had to delete the keepa.com string under the root/gcm/push_messaging_application_id_map node in the "Preferences" file in the profile folder. Or, I could goto opera://settings/reset and reset just settings.

https://girliemac.com/html5-notifications-webOS-style/

and i get notification. Still when i want to register to web push notification on Keepa.com, for example, I get the error message i posted.

If you force notification of course it pops out, but opera fails to register to the subscription to the service.

In Opera, goto https://example.com and hit ctrl + shift + j to open the console in the developer tools.

Type:

Notification.requestPermission().then(permission => {
  alert("Permission: " + permission);
});

and press enter.

When asked to allow notifications for example.com, choose "yes". You should then see an alert dialog saying the permission was granted.

Then, in Windows, goto "Settings -> System -> Notifications", make sure notifications are enabled, "Do not disturb" is disabled and there's no focus session enabled. Then, see if Opera is in the notification app list (it should be now if it wasn't). If it is, click "Opera" in the list and make sure its notification settings are correct.

Then, restart Opera.

Then, go back to https://example.com/, open the console again, type:

new Notification("Test notification from example.com");

and press enter to test that notifications work for the site.

Does all that work at least?

It does for me, but I'm on 23H2.

This issue is certainly something we will look into. We plan to investigate it internally and may reach out with further questions.

To @wetsmurfette: We understand your frustration regarding this matter. However, it's important to maintain a respectful tone in our interactions. When @leocg asked clarifying questions, the response was quite harsh. Constructive communication is key to resolving issues effectively.