When using session variables within a ColdFusion MX 6.1 application, the following error may occur if J2EE session management is enabled in the ColdFusion Administrator:
Error Occurred While Processing Request
Session is invalid
The error is generated when the underlying J2EE session times out before the ColdFusion session times out.
For more information, and for a workaround, see the following TechNote:
ColdFusion MX 6.1: Session is Invalid Error When Using J2EE Session Management