I started out creating a macOS 15.5 guest on my macOS 15.5 host (an Intel 16" 2019 MacBook Pro, MacBookPro16,1). This worked fine. Then I copied over the InstallAssistant.pkg file from a macOS 26 Beta 3 full installer, ran this to copy the full installer to /Applications, then ran "Install macOS 26 Beta". This worked, after a fashion. But it was *very* slow, and the VM I ended up has a badly broken UI and is very unstable. The Desktop is solid grey, and the Dock is completely missing. I can do things there, but it's *incredibly* slow -- it took more than an hour to run the XCode 16 Beta 3 for the first time, and another hour to install the Beta 2 Commandline Tools. The VM often hangs or crashes. So ... As I understand it, Parallels still supports macOS guests on Apple Intel boxes. Are they working to fix these problems? Will we be able to count on running the macOS 26 release as a guest in a Parallels VM on an Intel box?
I am having the same issue. (2019 16" MacBook Pro - Intel I7 32GB Ram). I was not able to log into my AppleID from a macOS 15.5 VM I created to enable the beta program that I joined, so I created a bootable USB containing the installation files for the 15.6 (macOS 26) Beta. After installation, the VM was extremely slow. Application icons appeared and disappeared randomly. Safari would not stay open for more than 20-30 seconds before crashing with an error complaining about the com.apple.driver.AppleParavirtGPUMetal driver used for graphics. I tried turning off the option to always use accelerated graphics and I upped the graphics memory to 512MB to see if that would help and it did not. Applications either crash shortly after opening or do not function correctly at all.
Judging by the "Parallels Desktop 26 for Mac system requirements" (https://kb.parallels.com/en/124223), the next (current?) version of Parallels (version 26) isn't going to support Intel guests or hosts. I upgraded Parallels 20 to the latest version (20.4.1), and still get the results I reported above.
Oops, I should have said that it doesn't seem Parallels 26 will support Intel hosts or guests on macOS 26.
