paypal - Error code 81002 Method is not supported - php

Question

My problem is related to this specific error:
I'm doing a form to contain data that have to be passed to the server to obtain the token, but probably i haven't understood some concepts about doing this
Here is my form
<form method="post" action="https://api-3t.sandbox.paypal.com/nvp">
<input type="hidden" name="USER" value="Apiuser"/>
<input type="hidden" name="PWD" value="Apipass"/>
<input type="hidden" name="SIGNATURE" value="Apisignature"/>
<input type="hidden" name="VERSION" value="52.0"/>
<input type="hidden" name="PAYMENTACTION" value="Sale"/>
<input name="AMT" value="19.95"/>
<input type="hidden" name="RETURNURL" value="http://www.YourReturnURL.com"/>
<input type="hidden" name="CANCELURL" value="http://www.YourCancelURL.com"/>
<input type="image" name="METHOD" src="https://www.paypal.com/it_IT/IT/i/btn/btn_xpressCheckout.gif" value="SetExpressCheckout"/>
</form>
And here is my function
if (isset($_POST['METHOD'])) {
$API_UserName = urlencode("Apiuser");
$API_PassWord = urlencode("Apipass");
$API_Signature = urlencode("Apisignature");
$return_url = "http://www.myurl.com";
$cancel_url = "http://www.myurl.com";
$version = urlencode('52.0');
$nvpreq = "USER=$API_UserName&PWD=$API_PassWord&SIGNATURE=$API_Signature&VERSION=$version&PAYMENTACTION=Sale&AMT=19.95&RETURNURL=$return_url&CANCELURL=$cancel_url&METHOD=SetExpressCheckout";
}
Is seems that something is wrong, can you give me a tip please?
Thanks a lot

Answer 1

Have you checked that you are not encoding the parameters twice? Im my case that was happening though http_build_query() and some default setting which was unstable for some reason due to being changed somewhere during runtime.
Basically your final call should contain & and not &, for me the final curl call for some reason ended up with being encoded as &.
Make sure you are not encoding twize, and if using http_build_query() update your function so it will be explicit on the encoding part:
from: http_build_query($requestParameters)
to: http_build_query($requestParameters,'','&')
The difference is that the last version will explicitly use & as delimiter while the first will use the default, so be sure.