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We want to thank the community members who have contributed their time and expertise to help others with their Apple products.
The Apple Support Community will permanently close on November 20, 2026. Starting today, the site will no longer accept new posts and is available in a read-only state.
You can continue to find trusted guidance and support on the official Apple Support site.
We want to thank the community members who have contributed their time and expertise to help others with their Apple products.
trying to do time machine backup. connected and selected external hard disc drive. I get the message "there was an error preparing "extreme SSD". "couldn't unmount disk". what does this mean and what do I do?
MacBook Pro 16″, macOS 12.6
lilayda wrote:
trying to do time machine backup. connected and selected external hard disc drive. I get the message "there was an error preparing "extreme SSD". "couldn't unmount disk". what does this mean and what do I do?
From the Terminal.app you can umount, and try again
copy and paste:
diskutil umount
notice the trailing blank space, drag your external from the Desktop onto the Terminal window to complete the path, proceed using the enter\return key...
ex.
MacBook-Pro ~ % diskutil umount /Volumes/Install\ macOS\ Ventura
Volume Install macOS Ventura on disk2s2 unmounted
MacBook-Pro ~ %
ref:
Back up your Mac Back up your Mac with Time Machine - Apple Support
couldn't unmount disk