I've been working happily with Parallels 8 under Mavericks with Snow Leopard Server as the guest. I use it daily. Recently every time I open Parallels I've been getting these warnings saying that I must upgrade to Parallels 10 or it's not going to work on Yosemite. I'm in no hurry to go to Yosemite but in preparation for when I do bought the upgrade. Today I have upgraded Parallels but now Snow Leopard Server won't boot. Just sits there with the Apple icon and a never ending spinner and then the Apple goes to a circle with a line through it. I appear to be dead in the water and have no idea what to do to fix it.
I fixed this. Somehow the installation process had corrupted my .pvm file which was causing the boot to fail. I had an external backup of the pvm file and overwrote the corrupted one and was then able to get it to work in Parallels 10. It wasn't totally straightforward so here's how should anyone else be in my situation: First find your .pvm file (mine was is users/shared/Parallels) and back it up if it's not already! After following the Parallels upgrade process start the virtual machine which then loads PTools. It says to restart the virtual which goes to the beach-ball and stays there rather than restarting properly. At this point go to Action/Stop which closes the virtual (after a warning which I dismissed). Now when you start Snow Leopard Server it loads and work properly.
Bob_Kerr's advice "At this point go to Action/Stop which closes the virtual (after a warning which I dismissed). Now when you start Snow Leopard Server it loads and work properly." was very helpful but on it's own did not quite do the job for me. I tried many time to import existing Leopard Server and Snow Leopard Server hard drive files from a Parallels 8 installation under Mac 10.8.5. Each time something different would happen - no Finder Menu Bar, no Dock, no internet access, can't change from one account to another, can't restart (except by stopping and relaunching) etc. I then went back to earlier versions of the files from a back-up perhaps a year and a half old. That seemed to fix Snow Leopard Server, but not Leopard. Eventually I assigned 2 processors instead of the 1 processor which seemed to be the default. (Yes, I know that's 2 virtual processors.) That did it! No more problems - for now. This is on a 5k iMac i7 running 10.10.1 with Parallels 10.
Since your post I too have assigned 2 processors instead of 1 and performance is much better. Thanks. (When I was first having the problem I raised a support ticket. That's nearly a week ago and still waiting for a reply. Looks like we need this forum.)
A big thanks, guys. I NEED to use Canvas (a legacy Mac application that still has quite a few users) and managed to get Snow Leopard Server working using your hints above. It is quirky: every time I start up Snow Leopard, Parallels Installation Agent attempts to install Parallels Tools and then asks to Restart the system (Snow Leopard). If you choose Restart it does not restart properly, just hangs with a scrambled top part of screen as it tries to shut down the system. I just choose "Postpone" and then Snow Leopard functions fine. No PTools, but I can live without them. Shutdown doesn't work, so I use Menu>Actions>Stop.
