VMware Converter can be awesome and a hassle at the same time. I have used it A LOT. I must say it is a great tool, but under some circumstances, even though you are converting a supported system which is the same as one you’ve done previously, it may fail (but the ones you did previously worked perfectly!).
There are many factor why the converter could fail. The most common issues are blocked ports (firewall). Unfortunately, even though the conversion has started and you are seeing the progress bar, it does not mean that it will finish without issues.
The chart below will help you to determine the possible issues based on the progression percentage level. It is also usually indicated in the conversion status panel.
|1%||VSS, Remove multiple VSS-providers from registry (KB)|
|1%||Unable to start the change tracking driver, disable User Account Control (KB)|
|2%||Network issue, set speed/duplex to auto/auto (Link)|
|2-96%||Multiple, IP/DNS/Hardware (KB | KB | KB)|
|3%||DNS issue, set DNS suffix (KB)|
|3-92%||Reducing disk volume size, Checkdisk (KB)|
|95-99%||Fails at reconfiguration, missing files or drivers (KB)|
|96%||Unable to find the system volume, Windows Boot manager (KB | KB)|
|97%||No Active Partitions, break software mirror (KB)|
|97-99%||Inaccessible_boot_device, driver issue (KB | KB)|
|98%||Unable to create, 3GB switch boot.ini (KB)|
|99%||Unable to determine guest OS, boot.ini (KB)|
|VMware Knowledge Base [KB]|