Hi @dodolo
Is your Mattermost server behind a reverse proxy or load balancer? If so, which one?
The reason I ask is because this error is generated by the Golang HTTP server library, and according to the source code this is what protocol requires if the client can’t accept push promises. From line 4997 in http/h2_bundle.go:
// A client cannot push. Thus, servers MUST treat the receipt of a PUSH_PROMISE
// frame as a connection error (Section 5.4.1) of type PROTOCOL_ERROR
There are a few other places where the PROTOCOL_ERROR is raised without any additional information in that file - lines 5019, 5038, and 5070 - and they all seem related to the Mattermost server pushing information to the client.