Request header field Access-Control-Allow-Headers is not allowed by Access-Control-Allow-Headers

Question

I\'m trying to send files to my server with a post request, but when it sends it causes the error:

Request header field Content-Type is not allowed by

Answer 1

The headers you are trying to set are response headers. They have to be provided, in the response, by the server you are making the request to.

They have no place being set on the client. It would be pointless having a means to grant permissions if they could be granted by the site that wanted permission instead of the site that owned the data.