Updated 500 response to be json

Author: schnuerle

general-information.md

@@ -176,7 +176,7 @@ During the Beta period for this feature, location and telemetry data remain requ
 - **404:** Not Found: Object does not exist, returned on `GET` or `POST` operations if the object does not exist.
 - **406:** MDS version in Accept header is unsupported or invalid.
 - **409:** Conflict: `POST` operations when an object already exists and an update is not possible.
-- **500:** Internal server error: In this case, the answer may contain a `text/plain` body with an error message for troubleshooting.
+- **500:** Internal server error: In this case, the answer should contain a `application/json` body with an [error message](#error-messages) for troubleshooting.
 
 ### Error Messages