What's the current exact version of ESXi running on this hardware ?
You are already running the maximum major version ESXi 6.0 U3 that this hardware supports. Hence you can apply the minor patch on this version.
ESXi 6.0 EP 21 is express patch which is part of Update 3 build only.
And - one more question - thanks for the reply above.
I applied that patch to a standalone esxi host, and all was well.
I have a vCenter server(s) that need to be patched as well, both are at version 6.0.0, build 5112529
I am looking for the patch file for this version, and it is running on HP DL380 Gen8 hardware.
I will continue to look the for the procedure and if we have VUM, we can update the hosts on
the vCenter server(s)
Yes, using update manager you can patch multiple hosts at the same time.