E-Maculation

I have used the New World ROM from Redundant Robot and Mac OS 9.0.4 ISO from WinWorld running on a MacBook Air (11-inch, Mid 2011) with macOS High Sierra 10.13.4. When I try to install Mac OS 9 in SheepShaver, I get this error:

The system software on the startup disk only functions on the original media, not if copied to another drive.

If you can help, thank you in advance.

The most common issue of the error you got is an unlocked CD image.
For a clean install from a MacOS CD image, the image has to be locked on the host OS.

Other than that, best pick a matching toast file from Macintoshgarden.
http://macintoshgarden.org/apps/mac-os- ... 3-firewire