This was a very common situation where I experienced in few of the environments when I was trying to perform a Storage vMotion of a Virtual Machine, and it failed with the error message Incompatible Device Backing Specified For Device “14”. This number can be changed according to your Virtual Machine configuration.
The error message appeared in one of the Virtual Machine as follows.
Incompatible Device Backing Specified For Device “14”
There was no any significant configuration issues with the Virtual Machine and this caused due to the Network Adapter which was not connected and specified to any Virtual Network.
What I had to do is, just specify one of the available network and connect the Network Adapter.
After that, the Storage vMotion was successful. I hope this post will help someone who got similar issues with a Virtual Machines.