While trying to add ESXi host in vCenter 6, you may get below error.
A general system error occurred: Unable to get signed certificate for host: <HOSTNAME>. Error: Failed to connect to the remote host, reason = rpc _s_too_many_rem_connects (0x16c9a046).
This error occurs if you have replaced SSL certificates of VMware vCenter Server using VMCA and made VMCA as an Intermediate Certificate Authority.
Once you make VMCA as an intermediate Certificate authority, you need to wait for 24 hours to add new ESXi Host in vCenter.
This behavior is changed in VMware vCenter 6.0 Update 2 and later with the advanced setting vpxd.certmgmt.certs.minutesBefore
Login to vCenter server using Administrator credentials, Go to vCenter server settings and update key vpxd.certmgmt.certs.minutesBefore value to 10.
You can wait for 24 hours to add new Host in vCenter server or Add ESXi Hosts in vCenter before making VMCA as an Intermediate CA