Mac OS: AppleTalk "Port in Use" Error

While trying to print an error message appears stating the port is in use and AppleTalk needs to be inactive. Trying to disable AppleTalk using the Control Strip or the Chooser does not disable AppleTalk.

Making AppleTalk Inactive

The default networking option for the Macintosh is to use the printer port for AppleTalk. In order to use the printer port for a serial device it is necessary to stop using the printer port for AppleTalk. There are two ways to accomplish this. The first is to move AppleTalk to another port such as Ethernet (if you are connected to an active Ethernet network). The second method is to make AppleTalk inactive.

During the migration from Classic Networking to Open Transport, older components of the networking software have not been upgraded to fully support Open Transport. Two such components are the Chooser and the AppleTalk Switch Control Strip Module. If AppleTalk is made inactive using either the Chooser or the Control Strip then only Classic AppleTalk components are made inactive. Open Transport AppleTalk components are still active. When you attempt to use the printer port for a serial device, the following error messages (or similar messages) may result:

"Printer port is in use by another application"
"Cannot find printer"
".[XXX printer driver] requires that AppleTalk is inactive. Please make AppleTalk inactive."

Follow these steps to make AppleTalk inactive under Open Transport:

For information on making AppleTalk inactive within the Classic Networking architecture, please see article 30168: "Mac OS: Chooser Defaults to Modem Port"

For Mac OS 8.1 users, Apple Location Manager 2.0.1 offers a convenient way to turn AppleTalk on and off. For more information, please refer to the Read Me included with Apple Location Manager 2.0.1.

For more information on Apple Location Manager 2.0.1, please see article 26162: "Apple Location Manager 2.0.1: Description"

Published Date: Feb 20, 2012