When you try to add a new host to vCenter and you see the error:
Operation failed! A general system error occurred: Unable to get CSR from host.
This is probably the time difference between vcenter and the host.
You need to set the correct time on the host and then restart it. If this doesn’t help, you can temporarily disable verification:
Go to vCenter -> Configure -> Settings -> Advanced Settings -> vpxd.certmgmt.mode and replace the default value of “vmca” with “fingerprint”. Now try adding the host. Once successful, change the setting back to “vmca”.