The specified 'Data' parameter is not valid JSON.
- The data you submitted is not JSON, or
- A missing or poorly-encoded character makes your JSON fail to parse.
- You crafted the HTTP request yourself, and did not percent-encode the submitted JSON data in the form parameters.
- Use a tool like JSONLint to check the data you're sending for syntax errors.
- If you're crafting HTTP requests yourself, make sure all form data is percent-encoded.