Troubleshooting Tip: Unable to access FortiGate-VM GUI after renewed license with a 'License is invalid' error

While accessing the FortiGate-VM via the GUI, the following error can be seen:

Need to verify FortiGate VM has internet connectivity and can ping below FQDNs:

update.fortiguard.net 
guard.fortinet.net
service.fortiguard.net

To verify FortiGuard connectivity in the GUI: 

1. Go to Dashboard -> Status.
2. Check the Licenses widget. When FortiGate is connected to FortiGuard, a green check mark appears next to the available FortiGuard services. 

Once that is verified, open the support portal, on the top there are the option Services -> Asset Management -> Products -> My Assets -> Select the FortiGate Serial Number and download the license file which is highlighted below screenshot:


Later, upload the license file on the FortiGate GUI access page under 'Full License'.