The JSON specification requires that strings be sequences of characters wrapped in double quotes. For some time, we have parsed JSON data sent to our API that contained strings wrapped in single quotes (') rather than double quotes (") which the spec dictates.
Due to security reasons, we can no longer parse incoming JSON strings wrapped in single quotes, whether they appear as names (i.e. keys) or values.
Please inspect the JSON data you are sending to our API to ensure that all of your strings are properly double quoted. JSON strings that are single quoted will be considered malformed and will trigger a parse error. Beginning very soon, parse errors for single quoted strings will return HTTP status code 400 ("Bad Request").