SAP Missing Certificate & No Valid Maintenance Certificate Found

Sympton

Whenever you try to execute transaction code SPAM or SAINT, you'll prompted with a pop up box saying that your SAP system is missing maintenance certificate and  no valid maintenance certificate found for system <SID>

Caused

As of 2009, maintenance certificates are required to be able to install and maintain SAP Software using the tools Add-On Installation Tool and Support Package Manager. These maintenance certificates can be requested using SAP Solution Manager and distributed automatically to the systems to be maintained.

Solution

Request a new maintenance certificate for SAP service market place.