Content type was not provided or is not supported

Hi everyone, 

I am sending a post request to https://api.na3.adobesign.com/api/rest/v6/transientDocuments API with following 

headers: {
Authorization: 'Bearer XXXXXXXXXXXXXXXXXXXXXX'

Content-Type: 'applicatioin/pdf'

Content-Disposition: 'form-data; name="File"; filename="2ed892f1b5e55e2b6622575e57f87f5c"'
},
form: FormData {...}
method: 'POST'
}

but I am getting UNSUPPORTED_MEDIA_TYPE error. I tried changing content type to 'application/json' or 'multipart/form-data' but no luck either. 

Does anyone know a way to fix this? Thankyou