vMotion fails at 72%

This week I had a strange issue with vMotion. I tried to put a host in maintenance mode and it failed. There were some VM’s that didn’t want to be moved to another host. The error I saw was this:

Hmm. Why was this happening to only a couple of VMs? A quick look at the setting revealed something I didn’t see before. All of the VMs that were stuck had a serial port configuration that was pointing to a server.

So the first thing I tried was disconnecting the port and testing a vMotion. Bam! It worked!

But why did it fail with a connected port? I tried the vSPC URI. Nothing!! The network team confirmed that there was no record for this server and after re-adding it to DNS I could connect to the URI. And when I connected the port and tried a second vMotion it was working again.