Extremely high number of 404 returned by Chrome subscriptions (FCM endpoints)

[collimarco]

Starting from Jun 26 we noticed a very high number of Chrome subscriptions (https://fcm.googleapis.com/fcm/send/...) returning 404 errors. All these subscriptions were returning successful status codes in the previous days / months.

This gem then raises InvalidSubscription when a 404 is returned by the endpoint.

This seems like a serious issue in FCM...

I am opening this topic here in case someone is experiencing the same problem or has additional information to share.

[collimarco]

I have also opened an issue in the Chromium bug tracker:

https://issues.chromium.org/issues/349646659

[collimarco]

This is the exact response (from logs):

404 Not Found

A valid push subscription endpoint should be specified in the URL as such: https://fcm.googleapis.com/wp/dHIoDxE7Hdg:APA91bH1Zj0kNa...

Note: the endpoint in the response is not the real FCM endpoint, it seems to be just an example.

[welishr]

Hi this is an intended change where the stale tokens for devices, which have not been connected to FCM in over 270 days, will be considered as expired and invalid. If a request is sent to an invalid token, it will be rejected with a 404 error.

Messages sent to these tokens previously were accepted and then never delivered (because the target devices are inactive), FCM now responds with a 404 instead. We have verified that we have seen no change in our delivery rates over the last week, despite the increase in 404s returned

[collimarco]

@welishr Thanks for the information.

However some of our customers are complaining that they are also seeing a lower number of clicks. So this suggests that many valid subscriptions were also removed...

I see that since this change thee total no. of clicks has dropped from 24k/day to around 14k/day. So it is likely that these contained a lot of valid subscriptions too.
[number of notifications successfully sent on the left, number of clicks on the right]

This is a serious damage for us and for our customers.

Please inspect this issue and consider restoring all the subscriptions.