You must have a valid Spirent TestCenter Support Entitlement license to upgrade Spirent TestCenter applications. If your Support Entitlement license is not current, you will not be able to use the upgraded software. A Support license is current if its Version date (format YYYY.MM) is equal to or later than the Application Release Date associated with the Spirent TestCenter upgrade you want to install. Please follow steps in attached document to verify if you can upgrade your STC chassis.