Incorrect virtual start-up disc
I have encountered an issue with the recovery procedure described by MichaelLAX in post #68 on Page 3 of this discussion:
Troubleshooting "An invalid Mac OS version is installed"
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Using the Parallels SUSPEND feature and/or if there is anything that ends Parallels without a proper Shut Down (such as a crash of Parallels while Snow Leopard is running) could result in this file NOT being recreated. Since it will be missing when Parallels reboots Snow Leopard, the resulting error message "An invalid Mac OS version is installed" will appear.
Here is how to fix this problem:
1. Go to ~/Documents/Parallels/ and double-click your Mac OS X Snow Leopard.pvm BACKUP file created in Step Four.
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10. Keep the original copy of ServerVersion.plist on the Desktop for future use. Shut down the Backup Snow Leopard partition from the Apple Menu.
11. Quit Parallels and in the future the Backup Snow Leopard partition will always have both Macintosh HDs available if you must ever boot it up again and copy the ServerVersion.plist file to the lower /Macintosh HD/System/Library/CoreServices/ .
My main virtual Snow Leopard (vSL) machine crashed as can happen and led to the invalid Mac OS version message as described above. I had a recovery system in place, built exactly in accordance with Michael's instructions. But it too failed to boot up and gave the same error. At the time I blamed myself for being careless and not having closed down either virtual machine properly, but for other reasons (trouble with migration to ML from older installations) I had to rebuild my entire Mountain Lion system from a clean disc, and I thought I might as well do the Parallels and vSL install right over again.
This time I gave the virtual machines (VMs) different names ("OS X virtual Snow Leopard" and "OS X vSL recovery"), and I also renamed their hard discs ("v Snow Leopard HD" and "vSL recovery HD") from the default "Macintosh HD".
What I found was this. When the "OS X vSL recovery" VM is set up to mount the two virtual discs, on booting up the "OS X vSL recovery" VM, the boot disc used was always "v Snow Leopard HD". I know this because it is displayed on the boot up screen. This was true whatever I did (e.g. check Parallels Boot Order under the configuration options, select startup disc under System Preferences, etc). However if I removed Hard disc 2 (pointing at "v Snow Leopard HD", the one you might want to fix), then the boot disc is "vSL recovery HD" as expected.
If the two discs had the same name you would never notice what was going on.
This prevents the recovery procedure from working, since you cannot 'hot mount' another virtual disc (as far as I know). You have to use Configure and reboot, and that process fails as soon as the disc that needs fixing is included in the list to connect, as I have described.
I found a way round. I retrieved the old recovery VM from my backup disc, so this was not a clone of "OS X virtual Snow Leopard" (it was made before I reinstalled ML). This now booted up successfully, despite an error message saying that Hard Disc 2 could not be found. This was as expected since I had not copied in the original main VM. When I reconfigured this old VM to make Hard Disc 2 connect to "v Snow Leopard HD", saved and rebooted, Parallels used the correct boot file.
Michael may already have a theory about this - maybe I have missed some obvious setting. If I haven't missed anything vital, then this suggests that the recovery instructions in #68 need modifying. It looks as if cloning causes the trouble, so the solution would be to repeat the process of creating a vSL machine from the beginning of Step 2 in Michael's original post, whilst ensuring that the names used for the VM and the virtual HD are different.