DPC Streaming agent: Websocket getting HTTP 400

Maia
1

Platform: Azure, DPC/Streaming.

State: Streaming agent is using the same container image, so we reused the terraform image agent for CDC with slight modifications. Container image started but not communicating with DPC.

Error:
PlatformWebsocketConfiguration : Failed to send heartbeat

2025-09-15T09:51:33.400Z  WARN 20 --- [     parallel-1] m.n.a.p.w.PlatformWebsocketConfiguration : Failed to send heartbeat

java.util.concurrent.ExecutionException: jakarta.websocket.DeploymentException: The HTTP response from the server [400] did not permit the HTTP upgrade to WebSocket
	at java.base/java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:396) ~[na:na]
...

Reviewing updated ARM/ACI templates, I haven’t seen any websocket endpoint specified. Nor the “agent creation page” indicates a web socket url to be specified.
is this PLATFORM_WEBSOCKET_ENDPOINT variable not used anymore?
what’s causing http 400?

2

well, problem solved: check your existing variables in the container group, and remove platform websocked endpoint (if you’re using an older template as i did).
it’s running now, without that environment variable.