I am seeing the following messages in the logs
2017-05-24T06:42:20.707-05:00 error vpxd[04752] [Originator@6876 sub=Default opID=StatsUpdateQueryOptimizer-23f57fe8] [Vdb::GetConnection] Failed to obtain connection: 08001:101 2017-05-24T06:42:20.775-05:00 error vpxd[14260] [Originator@6876 sub=Default opID=StatsTruncateExpiredPartitions-29eb7f58] [Vdb::GetConnection] Failed to obtain connection: 08001:101 2017-05-24T06:42:20.785-05:00 error vpxd[14504] [Originator@6876 sub=Default opID=CollectRemoteStats-224a901] [Vdb::GetConnection] Failed to obtain connection: 08001:101
looks like the connection with DB is not good.
Can you go for a clean shutdown of DB server if it is remote and restart the machine.
Once DB is up and running, reboot the vcenter server.
Also check if the following article helps, take snapshot of VC before you modify any setting so that you may revert if the step doesnt workout
vCenter Server service does not shutdown when database connectivity is lost (2007542) | VMware KB