Cross vCenter vMotion keeps falling with error "Cannot connect to host"

Products

• VMware vCenter Server

Issue/Introduction

• Unable to cross vCenter migrate VM's between vCenters with error "cannot connect to host" 

Environment

vSphere vCenter 8

vSphere ESXI 8  

Cause

Network misconfigurations on the management Vmks can make cold migrations between hosts on different subnets  fail.

Resolution

Troubleshooting steps:

•  Make sure what type of migration this is  going to be:
  • cold (powered off) 
  • hot  (powered on)
• locate both hosts on the source and destination vCenters

Do the following both the source and destination hosts

For a hot migration

• Go into configuration/ networking 
  • go into Vmkernel adapter and check where Vmotion is set 
  • Go into TCP/IP and looked at the vmkernel gateway 
    • Note: if this does not belong to the network  then we have to change it to the correct IP 
      • this Change has to be done through the ESXI DCUI 
  • once those changes are done on both sides, we can use the following commands to test connectivity 

For a cold migration

• Go into configuration/ networking 
  • go into Vmkernel adapter and check where Management is set 
  • Go into TCP/IP and looked at the vmkernel gateway 
    • Note: if this does not belong to the network  then we have to change it to the correct IP 
      • this Change has to be done through the ESXI DCUI 
  • once those changes are done on both sides, we can use the following commands to test connectivity 

Command to see the network path

 

esxcfg-route -l 

• this should give us the VMKernel routes of this host 

Traceroute ( destination ip)

• this will show us all the hops that it has to go through to the destination side, or if we are not able to see the destination side 

 

If we are still having issues with moving vms to the destination 

Workaround 

Go to the ESXI ui were those VMs live 

- click on the VM on question 

- click on action and Export 

•  Export will be used to create an OVF file or template of this VM which can be downloaded it into your computer and moved into a USB so it can register it on the destination side 
• Note: make sure to select all of the check boxes as each one of them is a part of the virtual machine 

Additional Information

Cross vCenter VM migration fails with the error "Cannot connect to host"

Cross vCenter Migration and Clone requirements in VMware vSphere 6.x and later