On my site (https://nashvillemusicianssurvivalmanual.com/) when someone tries to make a purchase and clicks on the "Check out with PayPal" button (not the "Checkout" button), this error message comes up:

PayPal Payment Pro error: Security error
Security header is not valid

Nothing has changed on this site for quite a long time and it has been working fine until recently.

Can anyone tell what is going on?

The same error was reported here

https://www.ecommercetemplates.com/support/topic.asp?TOPIC_ID=113950

What Paypal service is this? Paypal express, or paypal payments?

David

I do not have the API Credentials set up. I have clicked the "Email address to receive PayPal Payments" and entered the correct email address in there. It has been set up that way for about 10 years.

This happens when you click on the "Check out with PayPal" button - which is PayPal express, I assume.

When you click on "Checkout" and go through the process of entering your information and then being sent to PayPal, it works fine with no error message.

What do I need to do?

With that other thread, it may be possible there was some communication there that wasn't part of the thread.
I'll send a message to Vince and see if he want take a look at your post here.

Thanks,
David

I think that previously you could use PayPal Payments Pro by just entering an email address and fill in the necessary credentials later, and some people left things like that. But I think that PayPal may have stopped this and you need to have the credentials setup in the Payment Providers admin page for PayPal Express or PayPal Direct Payments. Could you check to see if that's the case?

Vince

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