The system can’t unmount the disk you are currently booted from.

Wait until the formatting process is done.

Wait until the process is ready in the Task to-do list on the right.

Install and run the software from the Applications folder.To format the drive with Stellar Partition Manager: You can also use this software to create a bootable DMG and load the system from it instead of the external drive. Formatting the hard drive or partition scheme will recreate a new HFS file structure on the hard drive, which will be free from cryptic errors. Use Stellar Partition Manager when macOS can not format, erase and repair the Mac hard drive or a volume due to the “couldn’t unmount disk” error. Stellar Partition Manager is an alternative to Disk Utility that allows performing various types of disk manipulations: create, hide, delete, resize and mount a volume. Fixing with Stellar Partition Manager Software For your convenience, we have structured instructions into step-by-step guides that are easy to follow. This includes using Stellar Partition Manager software, Disk Utility, or Terminal. There are several different ways to fix the “couldn’t unmount disk” error message on Mac. How to Fix “Couldn’t Unmount Disk” Error on Mac Use Stellar Data Recovery Professional for Mac if you encounter any kind of data loss and are in need of a quick and easy data recovery solution. Make sure to use Time Machine or other third-party services to backup your Mac and protect your files.

This becomes especially important whenever you try to fix any disk-related problems, including when you can’t unmount the disk on Mac. We all know that it is recommended to do regular Mac backups. Before Fixing the “Couldn’t Unmount Disk” Error Trying to perform any drive modifications would fail to give you the “couldn’t unmount disk” error message. You are also unable to partition, reformat or erase the disk you are currently booted from. The system won’t allow you to do anything if some other application or process uses the drive. Why is Mac Giving You the “Couldn’t Unmount Disk” ErrorĬan’t unmount disk on Mac usually happens when you try to do some manipulations with the external or internal drive. How to Fix “Couldn’t Unmount Disk” Error on Mac.Before Fixing the “Couldn’t Unmount Disk” Error.Why is Mac Giving You the “Couldn’t Unmount Disk” Error.

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