I’m getting the same exact error message when using curl (from windows). I first thought this was a Windows-related issue. However, it looks like it’s caused by something else. Did anyone figure out what to do or did you give up? When I search for a solution on google, this thread pops up people with the same issue without a solution.
There was another person who had this same issue when using javascript to post. He said he had to add a JSON.stringify() to the body of the POST. I have no idea what that means when using curl.