I've downloaded Vmware image of FreeBSD 11.2-RELEASE of late July, and it appears that the resulting virtual machine can't be snapshot: creating a snapshot of this VM results in an immediate shutdown and in a light corruption of the VM.
Corruption can be reversed by manually editing the config file of the VM.
VMware ESXi 5.5.0 Update 3 (Build 3248547)
VM is installed on an NFS datastore
This datastore in served by a FreeBSD server (ZFS)
Not sure whether the vmdk available for download is somehow defective or non-compatible with my setup. It's the first time I'm hit with this kind of bug.
URL of the vmdk: https://download.freebsd.org/ftp/releases/VM-IMAGES/11.2-RELEASE/amd64/Latest/FreeBSD-11.2-RELEASE-amd64.vmdk.xz