Security Level: All-users
I read the other report on this error. My error happens in both Sandbox and Production mode of the module.
I have a valid SSL certificate on my domain that I recently installed.
Please refer to logs:
02.TIMESTAMP -> 2011-06-04T14:23:09Z
03.L_ERRORCODE0 -> 10002
04.L_SHORTMESSAGE0 -> Security error
05.L_LONGMESSAGE0 -> Security header is not valid
06.L_SEVERITYCODE0 -> Error
07.PayPal returned error
That is the exact error message I receive when I try to go through a checkout on the site.