No valid Maintenance Certificate found on AS Java with SID. For more information, refer to SAP Note 1236587 .
You get this message when your Hardware is changed or the existing certificate is expired or you have uninstalled SAP and installed SAP on the same hardware
To request a new maintenance certificate for an existing system
1. Go to service.sap.com/licensekeys
2. Request Keys from a List
3. Select the required SID from the list
4. Click Edit System
5. Click Change System and change the Version of product if you changing from Dual stack to Java
8. Enter email
You'll receive the license to your email
Apply License via NWA if it's a Java System, SLICENSE if its an ABAP system.