Troubleshooting Tip: Unable to validate VM license - Certificate failed verification. Error: 18 (self-signed certificate)

User will get the output below, indicating license validation failed.

upd_daemon[1980]-Received update request from pid=13496
upd_vm_process[602]-last warning 66 seconds ago
do_setup[349]-Starting SETUP
upd_act_setup[126]-Trying Setup, fmg=0
__upd_comm_rcv[1000]-data_len=24, pkg(buf=0x7ffe2b9c798c, sz=8516, pos=0)
__upd_fix_rx_pkg[1019]-Failed, length=24, no res header.
upd_act_setup[137]-Failed receiving setup response, fmg=0, ret=-1
upd_act_setup[149]-Setup failed, fmg=0.
do_setup[353]-SETUP failed

Run the debug below to identify the reason why the VM is unable to validate the license.

diagnose debug reset
diagnose debug console timestamp enable
diagnose debug application update -1
diagnose debug application forticldd -1
diagnose debug enable

Output:

The log indicates that the license validation failure is caused by an SSL certificate verification error.

At the time of the connection attempt, the SSL handshake failed due to a self-signed certificate:

Error Code 18 – Self-signed certificate

Depth 0 – The failure occurred at the server certificate level

This means the virtual machine does not trust the certificate presented by the server because it is self-signed and not issued by a trusted Certificate Authority (CA) in the VM’s trust store.

As a result, the SSL connection could not be established, leading to license validation failure.

If the certificate (check the certificate 'subject') originates from the proxy server or from any intermediate CA in the chain, these certificates must be properly imported into the FortiGate device.

Ensure that the entire certificate chain is loaded so that it is recognized and trusted during the SSL handshake.