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

magento-1.7paypal

I am trying to get my PayPal integration working but I have a problem. When I try to purchase anything using Website Payments Pro or Express Checkout, I get the following error.

PayPal gateway has rejected request. Timeout processing request (#10001: Internal Error).

When I first tried it with the live site it worked with Express Checkout but now it won't work.

Additional Info

Magento version: 1.7

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Best Answer

I had this problem. Can't explain it, but it was solved by simply removing the paypal credentials and disabling the solution. Then entering the credentials again and enabling.

Worked fine again after that.