Mac OS 9.1: Installer Only Updates the Startup Disk When Mac OS 8.5 or Later Is Installed

Symptom

Though a Macintosh computer meets the stated system requirements for Mac OS 9.1, an alert box appears with a message that you cannot use the installer on that Macintosh computer.

This may happen, for example, when started up from a hard disk that contains Mac OS 8.1.


Solution

1. Startup from the Mac OS 9.1 CD by pressing and holding the "c" key at system startup time. This prevents the older System Folder on the hard disk from being active.
2. After Mac OS 9.1 finishes installing, open the Startup Disk control panel from the Apple Menu.
3. Be sure that the hard disk is highlighted in this control panel. If it is not, click its icon.
4. Close the Startup Disk control panel.
5. Restart the computer. When you restart the computer, your updated Mac OS 9.1 System Folder will be active.