During boot, a kernel core dump that is not marked as previously read was found on the host's core dump partition. The ESXi instance fails. After the core dump is extracted (for example, by obtaining the vm-support tarball), future boots of the host no longer post this event.
This event is informational only and is a warning that the core dump was detected. However, the failure that produces the core dump has the usual effects.
Obtain the vm-support tarball and file a support request.