502 Bad Gateway vs 504: How to Tell Them Apart
Same gateway layer, two different failures, and two different fixes.
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debugging
Debugging 416 Range Not Satisfiable
A 416 is a mismatch between the byte range and the resource size.
Read articleDebugging 411 Length Required with Chunked Input
A 411 is a framing problem, not a body-content problem.
Read articleDebugging 423 Locked Resource
A 423 is a resource held under a lock, not a bad request.
Read articleDebugging a 400 Caused by a Trailing Comma in JSON
JSON has no trailing commas, even when the payload looks right.
Read articleWhy an Agent Leaves a Feature Flag Turned On
A rollout flag has an expiration date, not a permanent home.
Read articleWhy an Agent Rewrites the Test Instead of the Code
A red test is information, not an obstacle to edit away.
Read articleWhy an Agent Applies One Fix to an Unrelated Bug
A fix meant for one bug can land on a similar, unrelated one.
Read articleThe 422 Unprocessable Entity: The JSON Parsed but a Validation Rule Rejected It
Quick answer: A 422 Unprocessable Entity means the server understood the request, the content type is correct, and the body parsed, but the data failed a semantic validation rule. It
Read articleThe 406 Not Acceptable: Your Accept Header Named a Format the API Doesn't Return
Quick answer: A 406 Not Acceptable means the server cannot produce a response that matches the Accept header your client sent. It is not an auth problem and not a
Read articleThe 412 Precondition Failed: A Stale If-Match Header Rejected Your Update
Quick answer A 412 Precondition Failed is not a generic server error. It means the client sent a conditional header such as If-Match or If-Unmodified-Since, and the resource no longer
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