I'm experiencing the same issue. I installed Windows 10 Pro and today I upgraded from Parallels for Mac version 9 to version 11.
After having upgraded/installed version 11, I've chosen to create a VM from my Boot Camp partition. After this has been created, I see the screen which says "Upgrading My Boot Camp": "Preparing to configure your virtual machine..." - and then I get a VM window where it says there is no boot device found.
Then I manually tried to change my hard drive (I've got an SSD drive with the OSX system on it, and a SATA drive with the Boot Camp partition on it). By mistake, I chose the SSD and started the VM. Here, I thought I've ruined both systems - but fortunately that wasn't the case and I just ended up with that same VM window with the "no boot device found" message again. Then I went back into the config to change back to the SATA drive, but it had already been done automatically. I also verified that the proper partition was selected (and it already was). Then I tried to start the VM once again and this time around it booted up Windows 10 properly without issues. When I logged into Windows 10 the "Upgrading My Boot Camp" screen showed once again and a window popup said the configuration was completed successfully. Succeeding this popup was another popup saying there was an error initializing the sound card. I was about to send in a report but the popup disappeared and coherence mode was started - and I was back at the log in screen. When logging in, Windows 10 "disappeared" and I was able to once again choose to send a problem report regarding the sound card (which I did, support id #72577336).
After exiting coherence mode, I was able to use Windows 10 from my Boot Camp partition - but without having the sound card working.
EDIT: After a couple of VM reboots and after having reinstalled the Parallells tools, I can now hear sounds in my Win10 boot camp. So it now seems everything is working fine.
Last edited: Aug 22, 2015