Thanks for this. Although by the time i reverted version 20180.1000 downloaded but this worked with your method.
Just tried 20180 and had the exact same problem. Going to try to roll back to PD 14 to see if that works.
I've been a beta tester for a while. If I remember correctly, they invited me one year that I particularly pestered them with cases and comments....
Guys, I see a light at the end of the tunnel. Too tired to test now, but one of the symptoms of the problem is that a new VM, booting from the 20175 ISO, experiences the same failure, so I started poking around with a new VM. I found out that the VM boots correctly from the 20175 ISO if I select the "Enable nested virtualization" option in CPU & Memory. With that option off, it freezes, but wit that option selected, 20175 boots. Tomorrow I'll test by checking that option in my VM that doesn't update and going through the update hell again. Will post the results.
I was able to successfully get 20180 to load after rolling back to PD 14. I am wondering if anybody has also done this, and after installing 20175/20180, updated PD back to 15, and if so, did the VM still work?
Same here. Have tried disabling all USB and Bluetooth devices and disabling the Hypervisor but nothing works.
OK guys, workaround confirmed. In Parallels 15 or 16 (Tech Preview), just check the "Enable Nested virtualization" option under advanced in "CPU & Memory" section and the VMs will correctly boot and upgrade to 20175 and 20180. Tested on a MacBook Pro (mid-2012) running macOS Catalina and a MacBook Air (2019) running macOS Big Sur beta 3. As far as I have tested, the option has to remain checked (e.g. ON), because as soon as it's unchecked, the VM won't boot. Have reported the issue to parallels. If you try it, please post if it worked for you.
Unfortunately, that check box is not available on the standard version of Parallels. I had to upgrade to Pro just so I could install this build of Windows. After upgrading, checking the box, and installing it worked. A solution will still need to be found for those not on the Pro version.
Thank You Mr. AngeloR, You are my hero for the next days Great hint, it worked like a charme. Hopefully we can uncheck the option, when the final release is out. Regards from Germany
Thank's a lot! It works as you described. After installation of 20180 and uncheck the "Enable Nested virtualization" the VM also boot. Regards from Cologne, Germany
Will try unchecking it again. I tried it in 20175 and failed, but maybe in 20180 works (didn't try again). Thanks!
I am not shocked that the mods have not commented on this issue. I did read elsewhere that VMWare is going to update Fusion to fix the insider builds. I guess I will be switching VMs.
So, after listening to the deafening silence of Parallels on this issue, I installed PD 14 and the insider builds install perfectly. Does anyone know if we can have both installed at the same time? I was going to rename PD14 and then reinstall PD15 to see if I could keep both. After everything, it looks like PD 13 and 14 work great with the latest builds but not 15.