Flash Variables Not Working !!! - HTTP Status 500

Hi Everyone,

          I am facing an error with the Flash Varaible in BO 4.0. Whenever I enter a value in Flash Varaible and click SAVE or SAVE & CLOSE I recieve a

HTTP Status 500 error. I have also attached the error screen shot.

          I face this issue all over the landscape. Quick help is highly appriciated. Thanks.

Regards

Baranedhaaran S.