PayPal SOAP API - Express Checkout - Error 10002

Question

I'm trying to connect my website to the Paypal Sandbox in order to use the Express Checkout feature. I've used this link as reference but i keep getting the 10002 Error "Security header is not valid".

From the documentation this has to be a invalid credentials problem but if i made the request manually through soapUI it returns "Sucess", if i use the curl command it also works as expected.

Scenario: ASP.NET page with two Web References one to https://www.sandbox.paypal.com/wsdl/PayPalSvc.wsdl and another to https://www.paypalobjects.com/wsdl/PayPalSvc.wsdl, the given credentials are Username, Password and Signature as you can see in the following code snippet:

using CloudShop.com.paypal.sandbox.www;

namespace CloudShop
{      

    public static PayPalAPIAASoapBinding BuildPayPalWebservice()
    {
        UserIdPasswordType credentials = new UserIdPasswordType()
        {
            Username = CloudShopConf.PayPalAPIUsername,
            Password = CloudShopConf.PayPalAPIPassword,
            Signature = CloudShopConf.PayPalAPISignature
        };
        PayPalAPIAASoapBinding paypal = new PayPalAPIAASoapBinding();

        paypal.RequesterCredentials = new CustomSecurityHeaderType()
        {
            Credentials = credentials
        };

        return paypal;
    }

Right now i would like to know how to proceed with the debug. What could be wrong?

Wolfram Wolfram · Accepted Answer · 2012-07-02T13:42:30

Some ideas:

Check if you are using the Live-Credentials for the sandbox account.
Are you using https://api-3t.sandbox.paypal.com/2.0/ (especially the -3t part) as the endpoint? You should as you are using Signature authentication.
As usual, you should step through every setting you are using: protocol, API Endpoint, Version, Credentials etc. and compare you're manual SoapUI call with the information stored in you shop configuration.

I also found a blog article on this error that might help resolving this issue.

PayPal SOAP API - Express Checkout - Error 10002

1 Answers