Parsing Request Body in Scripted REST APIs — Avoid NullPointerException

Quick Answer

The correct diagnosis works backward from the error itself: a NullPointerException means the script tried to read a property off something that does not exist, and here that something is request.body. In a Scripted REST API, request.body is only populated when ServiceNow successfully parses the incoming payload into an object, and that parsing depends on the request arriving with the right Content-Type header, typically application/json, or the resource being configured to accept a body at all. If either of those is missing, request.body stays null, and the moment the script tries to reach into it with request.body.serial, it is really trying to read .serial off null, which is exactly what throws the exception. The fix in a scenario like this is to confirm the caller is sending the correct Content-Type and that the Scripted REST resource is set up to expect and parse a body, rather than assuming the payload arrives as a ready-made object automatically. This pattern shows up constantly in integration troubleshooting: whenever an error trace points to a null reference immediately after code that expects parsed request data, the underlying cause is almost always that the data never got parsed in the first place, so the next step is always to check how the request was sent and how the endpoint is configured to receive it before assuming the logic further down the script is at fault.