Error in linkedin media upload api - php

Question

I am trying to upload an image using linkedin api.
I already uploaded image in my server and now I want to upload the upoaded image url to linkedin. But I got the error
{ "serviceErrorCode":0,"message":"The request is not a multipart
request","status":400 }
$curl1 = curl_init();
$m_url="https://api.linkedin.com/media/upload";
$curl_header = array("Authorization:Bearer ".$access_token);
$uploadRequest = array(
'name'=>'media',
'filename' => basename($medias[0]),
'media_data' => base64_encode(file_get_contents($medias[0]))
);
curl_setopt_array($curl1, array(
CURLOPT_URL => $m_url,
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "POST",
CURLOPT_POSTFIELDS =>$uploadRequest,
CURLOPT_HTTPHEADER=>$curl_header,
));
$response1 = curl_exec($curl1);
$err1 = curl_error($curl1);
curl_close($curl1);
This is the request. Please anyone tell me What is the exact issue and how to sort this out.Thanks in advance.

Answer 1

Added header like this:
$curl_header=array("Content-Type:multipart/form-data",
"Authorization:Bearer ".$access_token);
And changed the post params like this
$curl1 = curl_init();
$m_url="https://api.linkedin.com/media/upload";
$uploadRequest['file'] = new CURLFile($img, 'image/png', basename($img));
$curl_header=array("Content-Type:multipart/form-data", "Authorization:Bearer ".$access_token);
curl_setopt_array($curl1, array(
CURLOPT_URL => $m_url,
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "POST",
CURLOPT_POSTFIELDS =>$uploadRequest,
CURLOPT_HTTPHEADER=>$curl_header,
));
$response1 = curl_exec($curl1);
$err1 = curl_error($curl1);
$status1 = curl_getinfo($curl1, CURLINFO_HTTP_CODE);
curl_close($curl1);