400 Bad Request: Could Not Transform XML to JSON

Membrane API Gateway returns 400 Bad Request when the xml2Json plugin cannot convert the XML request body into JSON. The client labeled the request as XML, but the body cannot be parsed.

The Error Response

The response contains the status 400 Bad Request, a detail that starts with Could not transform XML to JSON: followed by the parser's message, the problem type https://membrane-api.io/problems/internal and a link to this page. Although the type is internal, the status 400 tells you that the client's request body caused the problem. In development mode, the charset-from-header field shows the charset from the Content-Type header.

What the xml2Json Plugin Does

The xml2Json plugin converts message bodies with an XML Content-Type into JSON, for example to offer a JSON interface for an XML backend. Messages that are not labeled as XML are passed on unchanged. The same error in the response flow is described under Could not transform XML to JSON in the response.

Common Causes

The Body Is Not Well-Formed XML

The request is labeled as XML but its body is not well-formed XML, for example because it is truncated, has unclosed tags or is not XML at all. The parser's message is in the detail.

The XML Declaration Names an Unsupported Encoding

The XML declaration names an encoding that Java does not support, for example <?xml version="1.0" encoding="foo"?>. The detail then starts with Unsupported encoding:.

The Body Cannot Be Read

The request body cannot be read or decoded, because the Content-Encoding is wrong or the client aborted the transfer.

How to Fix It

1. Send well-formed XML with a supported encoding such as UTF-8.
2. Do not label content as XML that is not XML.
3. Check that the charset in the Content-Type header matches the actual encoding of the body.

Hide Details in Production

By default, Membrane runs in development mode and adds details to error responses that help you find the problem. These details may reveal information about your setup. In production, turn them off:

configuration:
  production: true

configuration:
  production: true

Add the configuration document to your apis.yaml and separate it from the APIs with ---. The status and title stay the same, but the details and the link to this page are left out.

Related Documentation

Configuration reference:

• xml2Json

Tutorials with runnable examples:

• XML to JSON

← All Membrane error messages