Firebase server sends old messages

[cbratschi]

PHP_GCM was working fine for a couple of weeks. During this time we collected more than 6000 subscribers on our website. Then suddenly Chrome users were getting the same old message again and again. Sending new messages caused the delivery of the same old message. Android users are not affected, only Chrome Web users.

We tried to contact Firebase support but they are not willing to support a third-party library or to provide any debugging support.

We are sending notifications without payload which is much quicker than the encryption needed for each single message. We also tried it with encrypted payloads but our production process dies after sending about 1300 messages. So far we could not find the root cause of this issue. However, in this case Firebase was sending the correct messages to our Chrome users.

In my opinion this is a clear bug in Firebase because the payload we send does not contain a two week old message. Does anyone else have similar issues?

Thanks,
Christoph