The snippet posted shows that the tablet server is unable to verify the TLS certificate generated for the tablet server because the certificate 'valid from' field is in the future.  That's most likely because the master host's clock is at least 1 second ahead of the tablet server host's clock.   Tablet server TLS certificates are generated by master when the tablet server connects to the master first time after starting up.  Tablet server will retry the connection with next heartbeat to the master, sending a new certificate signing request, and the master will generate a new certificate, with the validity date in the future, again.   I suspect that the error will continue to appear even if you restart Kudu, and restarting Kudu will not help. You need to synchronize clock across machines in the cluster, at least within the delta of 1 second.  If NTP does not work for you, I would recommend trying at least to run 'ntpdate' at every machine of your cluster prior to starting Kudu servers. ... View more