KEMP400 - Invalid Response From Kemp LoadMaster

Agent error code #KEMP400 indicates that Knocknoc reached the Kemp LoadMaster and received a response, but the response did not match the expected shape. The most common case is a non-success status carrying an error message in the body. Less commonly, a success response that failed to parse.

This usually points at a transient LoadMaster-side error or an upstream proxy rewriting the response. It is rarely caused by a Knocknoc misconfiguration.

Common causes include:

• The LoadMaster returned an error message Knocknoc could not map to a more specific code
• An HTTP proxy or reverse proxy between Knocknoc and the LoadMaster rewrote the response body
• The LoadMaster was briefly applying configuration when the request arrived

Steps to Resolve

Retry the Operation

If the error is transient, retrying after a short pause usually succeeds. If it persists across multiple grants, treat it as a real problem and investigate.

Compare the Raw Response

1. From a host that can reach the LoadMaster, run: curl -sk -u '<username>:<password>' 'https://<loadmaster-host>/access/aclcontrol?list=white&apiformat=json'
2. Compare the response with what you expect the LoadMaster API to return
3. If the body is HTML or an unexpected JSON shape, check for a proxy rewriting responses between Knocknoc and the LoadMaster

Still Having Issues?

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