During a vMotion operation, a virtual machine may unexpectedly fail to migrate, accompanied by the error message "Device 'Migrate' is not available" and "Connection closed by remote host, possibly due to timeout" This issue often occurs when a virtual machine is powered off from within the Guest OS simultaneously with the vMotion cutover process.
ESXi 8.0
vCenter Server 8.0
The migration failure is primarily caused by an external "power off" event initiated from within the Guest OS (e.g., shutdown, restart, or power management action) while the vMotion operation is in progress. When the virtual machine is powered off during the vMotion stun or migration phase, the vCenter server receives a VmPoweredOffEvent, leading to a VmFailedMigrateEvent with a GenericVmConfigFault error because the migration target device is no longer accessible.
Please do not perform power operations within the virtual machine's guest OS while vMotion is in progress.