How do issues like incorrect content types or malformed JSON/XML specifically lead to payload error codes?

Incorrect content types or malformed payloads directly lead to payload error codes because the server's parser cannot correctly interpret the incoming data. 1) **Incorrect Content-Type:** If the `Content-Type` header (e.g., `application/json`) does not match the actual body format (e.g., it's XML or plain text), the server will attempt to parse the body as JSON, fail, and often return a 'Bad Request' (HTTP 400) with a specific payload error code indicating a parsing failure, or 'Unsupported Media Type' (HTTP 415). 2) **Malformed JSON/XML:** If the payload itself contains syntax errors (e.g., missing quotes, misplaced commas in JSON, unclosed tags in XML), the server's parser will fail to deserialize it into an usable object. This typically results in an HTTP 400 status code with a payload error code like `MALFORMED_JSON_ERROR` or `XML_PARSE_ERROR`, detailing the syntax problem.