Facebook Error #100 when uploading Offline Conversions using Marketing API - facebook

Question

I am using the the Facebook Marketing API to upload offline conversions.
The attached code was working until about 2 weeks ago and now reports the following error.
{"error":{"message":"(#100) The parameter data is required","type":"OAuthException","code":100,"fbtrace_id":"HkpzkWB1I5g"}}
I don't understand why it should simply stop working after working as expected for so long. I don't know how to fix it. Any ideas?
$data=array();
$data["match_keys"]["email"]=$emails;
$data["match_keys"]["phone"]=$mobiles;
$data["match_keys"]["fn"]=hash("sha256",$first_name);
$data["match_keys"]["ln"]=hash("sha256",$last_name);
$data["match_keys"]["ln"]=hash("sha256",$last_name);
$data["match_keys"]["ct"]=hash("sha256",$suburb);
$data["match_keys"]["zip"]=hash("sha256",$postcode);
$data["match_keys"]["country"]=hash("sha256","Australia");
$data["event_time"] = strtotime($order_date);
$data["event_name"] = "Purchase";
$data["currency"] = "AUD";
$data["value"] = $order_total;
$data['order_id']=$order_id;
$access_token = '<access_token_0>';
// PURCHASE DATA
$data_json = json_encode(array($data));
$fields = array();
$fields['access_token'] = $access_token;
$fields['upload_tag'] = uniqid() // You should set a tag here (feel free to adjust)
$fields['data'] = $data_json;
$ch = curl_init();
curl_setopt_array($ch, array(
// Replace with your offline_event_set_id
CURLOPT_URL => "https://graph.facebook.com/v2.12/1696501357346693/events",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "POST",
CURLOPT_POSTFIELDS => http_build_query($fields),
CURLOPT_HTTPHEADER => array(
"cache-control: no-cache",
"content-type: multipart/form-data",
"Accept: application/json" ),
));
$result = curl_exec($ch);
echo "\nResult encode";
echo ($result);
if (curl_errno($ch)) {
echo 'Error:' . curl_error($ch);
}
curl_close ($ch);

Answer 1

Same thing just started happening here. Exact same problem. I had to play around for hours... But to get it working, I commented out
//"content-type: multipart/form-data",
and it started to work for me. Please let know if that also solves your problem.

Answer 2

It simply means that data is not sent as per documentation. I was facing this issue as in my case "contents" parameter was passing empty string, instead of documentation says that "contents" parameter should contain atleast 2 parameters, that is, quantity and id.
Go through documentation and you can compare your value format with documentation.
Here is link for documentation :- https://developers.facebook.com/docs/marketing-api/conversions-api/parameters/custom-data#content-ids