paypal express checkout =>Error: Security header is not valid

Question

Error : Security header is not valid Array

(     [TIMESTAMP] => 2014%2d04%2d29T07%3a24%3a29Z     [CORRELATIONID] => 6af6749c848d6     [ACK] => Failure     [VERSION] => 109%2e0     [BUILD] => 10800277     [L_ERRORCODE0] => 10002     [L_SHORTMESSAGE0] => Security%20error     [L_LONGMESSAGE0] => Security%20header%20is%20not%20valid     [L_SEVERITYCODE0] => Error ) 

I am getting this error again and again and cannot move ahead. I had checked all the api username, password and signature, all are correct, but the main problem is that, all the things are already stored in paypal sandbox account but it cannot give back to the page. I mean to say transection is shown in sandbox account but it cannot send forward to the display page. Am I wrong somewhere?

Answer 1

generally this error means you are not using the correct API credentials. If you are convinced your credentials are correct then take a look at your endpoint. Sandbox credentials will not be valid in the production environment and live credentials will produce this error in the sandbox

Answer 2

I had this issue because my login contained "+"(plus) sign. Finally I manually decoded it to "%2B" as described here http://www.zen-cart.com/showthread.php?80849-Plus-sign-%28-quot-quot-%29-in-user-name-causes-security-header-failure-in-Paypal-Express-Checkou and the issue gone.