https://developers.google.com/cloud-messaging/http-server-ref#interpret-downstream

We are normally suppose to update the endpoint token internally in case GCM return us a registration_id field

But this is out of scope for now

This is just a reminder, not to forget that we can get this information there

https://developers.google.com/cloud-messaging/http-server-ref#table4

Basically Google says "there is an error, you should probably retry later"

Not sure where to make the distinction "error" vs "temporary error" here

I can only try to make it individually per endpoint when it sends back a message description

Not with just the HTTP code, and that documentation

I get that. All I was saying is that we have "suggestions" to retry later also in other response objects (MPNS, at least).

The idea is to return a TEMPORARY_ERROR for all endpoints that should be retried later, and then the application can implement the retry logic based on that.

Here is the doc of GCM regarding this
Errors in the 500-599 range (such as 500 or 503) indicate that there was an internal error in the GCM connection server while trying to process the request, or that the server is temporarily unavailable (for example, because of timeouts). Sender must retry later, honoring any Retry-After header included in the response. Application servers must implement exponential back-off.

Let's say I mark all the endpoints status as TEMPORARY_ERROR, the application logic can retry them but not using those headers and methods

Maybe it's not a problem...