Security Header is not Valid

I found some posts in the forum for OpenCart 1.5 but none of the fixes worked for me.

I just replaced the api's on my site and with paypal, but this is still giving me the "Security header is not valid".

No posting came up under search for 2.0 open cart forum so I am placing one here and hoping I can get a resolution to the problem.

Site is "secondamendmentusa.com". SSL certificates are in place and working (according to sslshopper.com (I guess a ssl checking website)).

Browser cache has been reset and cookies had to be resent.

How do I get this to accept the paypal pro api's?

Excuse me, how did you solve the problem: security header is not valid OpenCart that gave you paypal when paying? Thanks for your help!

I know that this thread is old. In case someone else have the same issue, we fixed this on our OC 2.0.2.0,

1. Make sure that there is API User for your Paypal Express exist. (Users>API)
2. Uninstalled Paypal Express module then re-install it
3. Re-enter your API Username, API Password, API Signature on Paypal Express module
4. Regenerate password for your API User in Users>API

I know this thread is old, can someone explain how to set up these API credentials like Im not a coder please.

In particular, I have checked that I have an API user under system/users/api and indeed I do - it is listed as 'default' and i assume was set when OC was installed, but how do I link that default user to get Paypal Express Checkout to work?

i get a 'Security header is not valid ' message when I click the paypal button.

OC version 3.0.3.8

FedUpOfKent wrote: ↑

Wed Jan 12, 2022 5:40 am

I know this thread is old, can someone explain how to set up these API credentials like Im not a coder please.

In particular, I have checked that I have an API user under system/users/api and indeed I do - it is listed as 'default' and i assume was set when OC was installed, but how do I link that default user to get Paypal Express Checkout to work?

i get a 'Security header is not valid ' message when I click the paypal button.

OC version 3.0.3.8

Sorry, but you are mixing up a few things!
The API-user has nothing todo with the PayPal settings.

The API-user is for internal purposes only (e.g. editing orders), for PayPal you do not to be a "coder", instead simply creating the API Credentials inside your PayPal Business Account!