PushManager.subscribe fails with AbortError

kostkafil

kostkafil

Hello,

I encountered a persistent problem when trying to get a service worker script to subscribe to push notifications via PushManager.subscribe(..). After calling the function, Opera prompts the user to confirm that they want to allow notifications. Several seconds after confirmation, the subscription attempt fails with the following error:
“Uncaught (in promise) AbortError: Registration failed - push service error”.

The same process works without issue on other browsers, including Chrome and Firefox. It failed on stable version of Opera on both Linux and Windows.

Likely cause:

I tracked outgoing network traffic using Mitmproxy, and found that PushManager.subscribe(…) sends, on both Opera and Chrome, a https request to FCM (android.clients.google.com/c2dm/register3).

The requests from Chrome include headers of the form

app: com.chrome.linux
X-subtype: wp:https://www.mySite.com/#3A9FDAEB-1EI2-4X8D-823B-E2ABE9153-V2

and the Google backend responds with a valid registration token.

For Opera, the X-subtype is missing entirely, and the wp token is instead placed inside the app header:

app: wp:https://www.mySite.com/#3A9FDAEB-1EI2-4X8D-823B-E2ABE9153-V2

As a result, Opera receives the response “400: Error=invalid subtype”, and the subscription fails.

When I replayed the requests made by Opera, but modified the “app” and “X-subtype” to match the format used by Chrome, the subscriptions succeeded.

Has anyone else encounter this? Is this a known bug in Opera?

"Note: I originally submitted a more detailed report in November 2025 via the official bug reporter under ID: BUG-17550"