I am using Store with PayPal Express. I have entered my credentials from my PayPal account.

When I try to make a purchase I get the payment method error "Security header is not valid."

I have tried setting and unsetting the Require SSL connection for checkout and order tags setting in store - makes no diff.

I need help with where to look.

2 Answers 2


This sounds like an issue with PayPal credentials according to these threads:



If you are connecting to "Live", recheck your credentials and make sure you are using the correct ones for "Live".

If you are connecting to "Sandbox", make sure those credentials are correct.

  • Beat me to it! :) Feb 15, 2013 at 15:57
  • 1
    Thanks - that was it - my stupid copy/paste left off the last character of the signature Feb 15, 2013 at 16:22
  • Perfect. Glad you got it sorted.
    – Anna_MediaGirl
    Feb 15, 2013 at 16:24

Generally this happens when you are using PayPal live account credentials, but you have set the gateway to "Test Mode" in the Store settings, or vice versa.

Note that you can only set the PayPal gateway to test mode if you have created a PayPal developer account (this has completely separate credentials from your normal PayPal account).

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