I want to upload file to zoho using uploadFile method, but unfortunately i got this :

"Unable to process your request. Please verify whether you have entered proper method name,parameter and parameter values."

i am already tried this "https://help.zoho.com/portal/en/community/topic/unable-to-process-your-request-please-verify-whether-you-have-entered-proper-method-name-parameter-and-parameter-values" but  dose not work

$fields = array();
$fields['authtoken'] = $this->authtoken;
$fields['scope'] = "crmapi";
$fields['id'] = $id;
$fields['content'] = '@' . $content;
$ffilesize = filesize($content);
if ($ffilesize >  20000000)
{
    die("File size must be less than 20MB");
}


$zoho_url = "https://crm.zoho.com/crm/private/xml/$module/uploadFile";

$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']);
curl_setopt($ch, CURLOPT_TIMEOUT, 60);
curl_setopt($ch, CURLOPT_POST, count($fields));
@curl_setopt($ch, CURLOPT_POSTFIELDS, $fields);
$output = curl_exec($ch);
if ($err = curl_error($ch)) return $err;
curl_close($ch);
if($this->isError($output)){
    echo $this->error; 
}
return $output;