Occasionally we receive reports of odd system behavior, such as:
- When opening a document, the application on the backup volume is opened rather than the version from your startup disk
- When trying to update an application in App Store, the update appears to fail — the older version is always present
- The destination volume cannot be (gracefully) unmounted because various applications or files are in use
- When choosing Open With... from a Finder contextual menu, duplicates of your applications appear in the list
These problems consistently go away if the destination volume is ejected.
These problems are ultimately caused by problems with the LaunchServices database, which is an issue outside of the scope of the backup process. There are a few things that you can do to address the problem:
Disable Spotlight on the destination volume
Disabling Spotlight indexing on the destination volume should prevent new additions being made to the LaunchServices database that reference the destination. Open the Spotlight preference pane, click on the Privacy tab, then drag your destination volume into the privacy tab. Check whether applications still open by default from the destination volume, because this step may be enough to address the issue.
Configure CCC to eject the destination volume at the end of the backup task
In the Postflight section of CCC's Advanced Settings, you can configure CCC to unmount the destination when CCC has finished copying files to it. By keeping the destination volume unmounted, Finder and App Store will be unable to find applications on that volume. You'll save wear and tear on that hard drive by keeping it spun down as well.
Reset the LaunchServices database
macOS maintains a list of application-to-file-type associations in the LaunchServices database. That database is consulted every time you try to open a file or application. Sometimes that database becomes corrupted, or contains outdated or invalid information, and those discrepancies can lead to problems with opening documents or applications. You can use this Reset LaunchServices Register application to reset the LaunchServices database, then restart your Mac.
Big Sur+ users: GateKeeper will prevent you from running that script. You can paste the following into the Terminal application instead to reset the LaunchServices database:
sudo /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain system -domain user
Press the Return key after pasting that line into the Terminal window, then authenticate when prompted. Restart your computer for the change to take effect. macOS will automatically rebuild the LaunchServices database.