Paypal Express Checkout Error (Method Specified is not Supported) - php

Question

I am new to codeigniter and paypal. I am working on gocart(an open source eCommerce solution built on codeIgniter). I try to work on paypal API integrated in it, but its showing error as follows :
[ACK] => Failure [L_ERRORCODE0] => 81002 [L_SHORTMESSAGE0] => Unspecified Method [L_LONGMESSAGE0] => Method Specified is not Supported [L_SEVERITYCODE0] => Error
Below is my code : paypal_expres.php
$this->RETURN_URL = 'www.example.com';
$this->CANCEL_URL = 'www.example.com';
$this->currency = 'USD';
$this->host = "api-3t.sandbox.paypal.com";
$this->gate = 'https://www.sandbox.paypal.com/cgi-bin/webscr?';
public function doExpressCheckout($amount, $desc, $invoice='') {
$data = array(
'PAYMENTACTION' =>'Sale',
'AMT' => '24',
'RETURNURL' => $this->getReturnTo(),
'CANCELURL' => $this->getReturnToCancel(),
'CURRENCYCODE'=> $this->currency,
'METHOD' => 'SetExpressCheckout'
);
$query = $this->buildQuery($data);
$result = $this->response($query);
$response = $result->getContent();
$return = $this->responseParse($response);
echo '';
print_r($return);
echo '';
if ($return['ACK'] == 'Success') {
header('Location: '.$this->gate.'cmd=_express-checkout&useraction=commit&token='.$return['TOKEN'].'');
}
return($return);
}
public function doExpressCheckout($amount, $desc, $invoice='') {
$data = array(
'PAYMENTACTION' =>'Sale',
'AMT' => '24',
'RETURNURL' => $this->getReturnTo(),
'CANCELURL' => $this->getReturnToCancel(),
'CURRENCYCODE'=> $this->currency,
'METHOD' => 'SetExpressCheckout'
);
$query = $this->buildQuery($data);
$result = $this->response($query);
$response = $result->getContent();
$return = $this->responseParse($response);
echo '';
print_r($return);
echo '';
if ($return['ACK'] == 'Success') {
header('Location: '.$this->gate.'cmd=_express-checkout&useraction=commit&token='.$return['TOKEN'].'');
die();
}
return($return);
}
private function response($data) {
$result = $this->CI->httprequest->connect($data);
if ($result<400) return $this->CI->httprequest;
return false;
}
private function buildQuery($data = array()) {
$data['USER'] = $this->API_USERNAME;
$data['PWD'] = $this->API_PASSWORD;
$data['SIGNATURE'] = $this->API_SIGNATURE;
$data['VERSION'] = '56.0';
$query = http_build_query($data);
return $query;
}

Answer 1

When Paypal returns this message it's a case of transmit method, not the method argument/property.
As in Paypal only accepts POST.