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# Error Message: Volume UUID wasn't unique

## Problem:

More than one volume has the same Universal Unique IDentifier. As the name implies, these should be universally unique, with no two volumes ever having the same UUID.

Synk uses the volume UUIDs to locate the folders you want synchronized, so if more than one volume has the same UUID, it's ambiguous which volume it should work on.

## Try the following:

- Open /Applications/Utilities/Disk Utility.app
- In turn, select each volume and click Info in the toolbar. Compare the "Universal Unique Identifier" entries in the resulting window.
- Make a note of the "Disk Identifier" of each volume that shares a common UUID. It will look like "disk0s2" or similar.
- Open /Applications/Utilities/Terminal.app.
- For each volume that shared a common UUID, that is NOT the volume your computer is booted off of, reset its UUID as described below.

## To reset a volume's UUID:

- Open /Applications/Utilities/Disk Utility.app and /Applications/Utilities/Terminal.app.
- In Disk Utility, unmount the volume by selecting it and clicking "Unmount" in the toolbar.
- In Terminal, type `/System/Library/Filesystems/hfs.fs/hfs.util -s disk0s2`, substituting the actual "Disk Identifier" of the volume you found from Disk Utility.
- In Disk Utility, mount the volume by selecting it and clicking "Mount" in the toolbar.

## Important note:

You will need to reconfigure Synk for any folders on the affected volumes, so it can update its settings to use the new UUID.

## See also

Error Messages