HTTP POST to Agent URL Periodically Returning HTTP 600 Response

We’ve got a few devices out in the wild (production) that are periodically responding to our HTTP POST requests to the Agent URL with an HTTP 600 Response Code.

Problem occurs intermittently. It’s about a 70/30 split (600 Response vs. 200 Response/working) and only for some of the Agent URLs we hit.

Anyone know what this means / how to begin to address?

I’ve never even heard of a 600 code; pretty sure we’re not returning that.

Could you PM with a device ID or agent ID that has shown this so we can dig?

Actually, I dug and found several; only your agents are ever returning these, we’re not seeing anyone else get them.

Is there any way your agent code can return that? The return code generally comes from your agent code with some rare exceptions (the load balancers can return 503 for example).

You’re right, it’s definitely in our code. Thanks for your patience and the nudge in the right direction!

The IANA list of registered HTTP status codes is at It refers back to the HTTP specification (mostly, but also 7230, 7232, etc.).

To clarify: you should try to avoid inventing your own HTTP codes, because it’s confusing.

Aside: this (slightly sweary) tweet explains the meaning of the status code ranges.