I integrated the Paypal express checkout into our eCommerce system (NVP version 76.0, PHP 5.2) that has a bespoke checkout process. While in development mode (using the sandbox details) everything works but the moment I switch the signature information (username, password, api_signature and the paypal url) to the live Paypal account information it stopped working. It always responds with a error code: 10002 and message: Security header is not valid If I switch back to sandbox details it starts to work again.
Here is the error example:
TIMESTAMP: 2011-12-06T19:09:31Z
CORRELATIONID: cb966ebeb254d
ACK: Failure
VERSION: 76.0
BUILD: 2271164
L_ERRORCODE0: 10002
L_SHORTMESSAGE0: Security error
L_LONGMESSAGE0: Security header is not valid
L_SEVERITYCODE0: Error
I found some posts on stack overflow of people having the same problem but there solution didn't work @Paypal and I did some digging around (on google) and found that a lot of people experience this problem but there is no definitive solution or a thread that would outline what you need to change when you go live because just changing the details mentioned above (and in the paypal express checkout documentation) doesn't seem to work.
Did anyone find a solution to this problem or maybe I just missed something?