I created a virtual machine with an “independent persistent” disk.  This prevents VMware from being able to take snapshots.  Since the method for backing up an entire virtual machine on a stand-alone ESXi server is to take a snapshot and then copy the snapshot to a network location, this prevented me from being able to back up the server.  (I could only back up the virtual machine if I shut it down.)

I was able to correct the configuration by powering off the virtual machine and editing the virtual machine settings.