PayPal gateway has rejected request. Security header is not valid (#10002: Security error Magento

Question

up the pay-pal advance in magento . I have fill all the credentials in magento admin . BUt when i go to frontend and click pay-pal button it gives

Pa

Answer 1

If you are using PayPal Payments Advanced with Magento, you should be using your PayPal Manager credentials, and not your API Credentials.
This could be the reason you are getting Security Banner Header not valid 10002.
Here is the integration steps from Magento:
PayPal Advanced Integration with Magento

You need to setup Layout C in PayPal Manager PayPal Manager Login.
Make certain that you include your error URL, cancel URL, and Return URL. Magento is very good about telling you what URL you should be using.

After you have setup Layout C in PayPal Manager you need to use your Manager Credentials in Magento.
Just in case you need it, here is the information on setting up your Hosted Checkout Pages in PayPal Manager:
PayPal Hosted Checkout Pages

Here is the information on where to find your PayPal Manager credentials:

• Partner: Your PayPal Partner ID. Most direct Merchants have PayPal as the Partner
• Vendor: Your PayPal user login name. Also known as Merchant Login
• User: The ID of an additional user set up on your PayPal account. Same as Merchant login if you have not setup a separate user id in PayPal Manager.

Use your API Signature Credentials from your PayPal account for the Express Checkout setup.