I have an ASP.NET Core Web API project, with a controller and a controller method that has a parameter [FromBody] MyDTO dto.

When I call this method via REST request with an empty body, the framework returns a ProblemDetails object with something like this:

{
  "type": "https://xyz/Status-400",
  "title": "Bad Request",
  "status": 400,
  "errors": {
    "": [
      "A non-empty request body is required."
    ]
  },
  "trace-id": "..."
}

which is absolutely understandable.

But: when I call it with a request body like “[]” which is not a jsonObject but an array (whereas the controller method needs a single object), the ProblemDetails response object looks something like this:

{
  "type": "https://xyz/Status-400",
  "title": "Bad Request",
  "status": 400,
  "errors": {
    "$": [
      "The input was not valid."
    ]
  }
  },
  "trace-id": "..."
}

which again is somewhat “okayish” if one can assume that $ means request body (this message comes directly out of the ModelStateDictionary).

My questions are:

• How can the name of the key $ be changed?
• Should it be changed?