Mac OS: Extension Conflict Troubleshooting/Extensions Manager Features

This article explains how the Extensions Manager control panel works in Mac OS 7.5 through Mac OS 9, how to tell if your computer is experiencing a system extension conflict, how to troubleshoot system extension conflicts, and extension error messages.

This article has been archived and is no longer updated by Apple.

The Extensions Manager control panel was first included in System 7.5. It simplified extension conflict troubleshooting. In Mac OS 7.6, the Extensions Manager control panel went through a major update.

Question: What Is System Extension Conflict Troubleshooting?
Answer: Troubleshooting a system extension conflict is a process of elimination. The process requires that you restart the computer a number of times.

Question: How Do I Know if I Have A System Extension Conflict?
Answer: If you start up your computer with only the standard set of Mac OS system extensions enabled (Mac OS 8.x All or Mac OS 9.x All), and the faulty behavior no longer occurs, then the computer has a system extension conflict. Conversely, if the computer exhibits the faulty behavior with only the Mac OS All set enabled, perform a clean installation of system software.

Question: Is Disabling All the Extensions in the Extensions Manager the Same as Pressing the Shift Key at System Startup Time?
Answer: No. See article 17392: "Extensions Manager: Extensions Off Compared to Shift Down"

Extensions Manager Features

What Are Sets?

Figure 1 Set Image

An extension set can consist of system extensions, control panels, startup items, and shutdown items. The Selected Set pop-up menu displays the name of the selected set. Mac OS 8.x All, Mac OS 9.x All, Mac OS 8.x Base, and Mac OS 9.x Base are locked sets supplied by Apple and have a lock icon next to them. These extension sets are known to work and cannot be modified. You can, however, duplicate one of the sets and make modifications to the duplicate. My Settings is a generic name for a set that has not been named.

You can rename, duplicate, revert, and delete sets.

Figure 2 File Menu

Viewing Sets
While the Extensions Manager is open, you can change views by choosing one from the View Menu (see Figure 3). With View by Packages selected you can turn entire software packages on and off with a single click. This is useful when troubleshooting extension conflicts. Choosing View by Items results in a list of all your system extensions, control panels, and startup and shutdown items. This view is similar to the view offered by the Extensions Manager in System 7.5.

Figure 3 View Menu

Opening Extensions Manager at System Startup Time
Before the first system extension displays at system startup time, press the Space bar to open the Extensions Manager. The changes you make affect the computer right now, so you do not have to restart it. Click Continue to close the window, and to continue starting up the computer.

Question: Can I Back up My Extension List?
Answer: No. You can save a list of system extensions as a SimpleText document from the File Menu, though. You can also create a report of installed system extensions using Apple System Profiler.

Identifying Extensions
For more information on a particular item, click Show Item Information (See Figure 4). The availability of this information depends on whether or not the software vendor included it in the system extension. You can also choose Get Info from the Edit menu to find out more about a selected system extension.

Figure 4 Show Item Information

Question: What are the Extensions and Extensions (Disabled) Folders?

Figure 5 Extensions and Extensions (Disabled) folders

Answer: The System Folder has both an Extensions folder and an Extensions (Disabled) folder. The Extensions Manager control panel creates an Extensions (Disabled) folder if one doesn't already exist. When you close the Extensions Manager control panel after making changes, the Finder moves all the enabled or disabled extensions to the appropriate folder. For example, if you disable an extension in the Extensions Manager control panel, it is moved from the Extensions folder to the Extensions (Disabled) folder when you close the control panel.

Troubleshooting an Extension Conflict

It is important to note that when you disable an extension and restart the computer, a part of the system may lose functionality while the extension is disabled. For example, disabling a printer software extension may prevent the system from printing. When the extension is enabled and the computer restarted, the system regains printing capability. This behavior is normal and should not be cause for alarm during the troubleshooting process.

Follow these steps to troubleshoot an extension conflict:

  • 1. Use the "Save set as text" command in the Extension Manager's File menu to save the set of system extensions that has the issue.
    2. Choose Mac OS 8.x All, Mac OS 9.x All, Mac OS 8.x Base, or Mac OS 9.x Base from the pop-up menu.
    3. Restart the computer. If the faulty behavior still occurs, try disabling the extensions by restarting and pressing the Shift key while the computer starts up. If the behavior disappears, perform a clean installation of the system software.
    4. Duplicate the locked set you chose in step 2.
    5. Name the duplicate set "Troubleshooting" or "Test."
    6. Determine which of the extensions from the set that you saved in Step 1 are not in the Troubleshooting set.
    7. Turn on three to five of those items from the Troubleshooting set.
    8. Restart the computer.
    9. Continue this process of turning on items and restarting the computer until the faulty behavior occurs again. You can also turn on a package at a time if you view items as packages. Once the faulty behavior reoccurs, you know that it was one of the last items you turned on that is causing the conflict.
    10. Turn off the items in the last group one at a time until you determine which item it is.
    11. Once you have found the faulty extension, check for version incompatibilities with other extensions or Mac OS. If you have determined that they are compatible, then try deleting the extension and reinstalling it from the installation disks.
    12. Use a disk repair utility such as Disk First Aid to check and repair the computer's hard disk.
    13. If you reinstall an application program, drag its preference file(s) from the Preference Folder to the Trash, and choose Empty Trash from the Special menu.
    14. If you are still having difficulties, contact the software vendor for further assistance.
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