Unable to connect FortiGuard servers

Hey, I renewed the license of my fortigate from the portal but it does not update in my fortigate because it shows that it cannot connect to the fortiguard servers, someone knows what to do: it showed me the following error output, in addition to without problem I can ping service.fortiguard.net and update.fortiguard.net

[359] __ssl_crl_verify_cb: Cert error 20, unable to get local issuer certificate. Depth 0