After installing Workstation 15.5 on my Fedora 29 system, I set a Windows 10 client to upgrade to 1903.
Many times, as in 10-15 times, during the Windows download the Windows client froze with the following Linux Workstation pop up:
Only "Cancel" worked, after which I got a warning about an unsychronized vmdk.
Clearing the "lock" and restarting, progressed farther. After more than a dozen repetitions it appears to be "installing". Still waiting ...