Mac OS X 10.3: Software Update "The update could not be verified and expanded" alert

Note: This document applies to Mac OS X 10.3 through 10.3.9.

An option in Software Update preferences allows you to download important updates in the background. If you open Software Update preferences, click Check Now, and begin downloading an update at the same time, this message appears:

"The update could not be verified and expanded correctly. Make sure you have permission to write to /tmp/###/TemporaryItems/com.apple.SoftwareUpdate, then try again."

(Where ### is the logged in user's user id.)

Follow these steps:

1. Deselect "Download important updates in the background" in Software Update preferences.
2. From the Finder Go menu, choose Home.
3. Double-click the Library folder.
4. Double-click the Caches folder.
5. Look for a folder named "com.apple.SoftwareUpdate", then drag it to the Trash.
6. Empty the Trash.
7. Restart.
8. Log in and test Software Update.

If the error appears again, repair permissions with Disk Utility. After the repair is complete, try Software Update again.

If the issue persists, download standalone updates from Apple Downloads as a workaround.