How to find the root cause for config update error

We are running Kong with the Ingress Controller, db-less. When we tried upgrading to Kong 3.4, KIC 2.28, we see a “failed posting new config” error (see below). The generic question is: How do we find the root cause when we see such an error? There is no indication for what is wrong.

level=error msg="could not update kong admin" error="performing update for https://localhost:8444 failed: failed posting new config to /config: got status code 400" subsystem=dataplane-synchronizer

Not sure if its relevant but did you look at the Kubernetes events which can contain information on config failures.

@JohnWilliams Thanks! I check Kubernetes events for other issues but didn’t think to check for a Kong config issue. We’ve rolled back for now, but will try again soon, and will keep this in mind.