Mac OS X: Classic Will Not Finish Starting Up - Extension Conflict or "Bus Error"

During Classic startup you may see signs of an extension conflict or "bus error." Use this document to troubleshoot the issue.
Note: This technical document covers one aspect of troubleshooting the Classic environment. For more information, see technical document 106677: "Mac OS X: Troubleshooting the Classic Environment"

Symptom

Classic begins to start up, but it does not finish. If you have clicked the disclosure triangle to view the entire Classic startup window, you may see evidence of an extension conflict or a "bus error." In an extension conflict, you may note that the process halts as the extension icons are being drawn across the bottom of the Classic startup window. If a "bus error" occurs, an alert box with a message may appear.


Solution

You must troubleshoot an extensions conflict or "bus error" just as you would were the computer actually starting up from Mac OS 9, with one exception: You may access the Extensions Manager through the Classic pane of System Preferences. Follow these steps:

When Classic starts up, Extensions Manager will open and you can proceed according to standard extensions troubleshooting procedures. For more information on using Extensions Manager, see technical document 30929: "Mac OS: Extension Conflict Troubleshooting/Extensions Manager Features"
Published Date: Oct 7, 2016