Unable to Uninstall Disk 69888 on Mac | Top 6 Ways

If you encounter the "Unable to unmount disk 69888" error on your MacBook, it means that you're attempting to partition, format, or delete a disk. Unfortunately, you can't complete this action because the operating system doesn't allow it.

After all, the disk might have been in use by some other application or there was a hardware failure. Today's article will discuss everything about this error, its causes, and solutions.

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On Mac, you may encounter the inexperienced unmount disk issue when you fail to delete, erase, or partition an external or internal drive (including HDD or SSD, Time Machine backup disk, USB flash drive, and built-in Fusion drive). This will lead to multiple errors, with one of the most prominent being "Error 69888: Can't unmount the disk".

Why Do You Get the Error "Unable to Unmount Disk 69888" on Mac?

When you attempt to perform certain operations on an internal or external disk in macOS, you may encounter the error “disk69888 can't be unmounted.” For example, your Mac might show a disk0s2 not mounted issue. If another process or app is using the disk, your MacBook won't let you make changes.

You might also be unable to format, partition, or delete the disk that was most recently booted. However, you can try to switch drives without receiving error 69888.

How to fix the "Cannot Unmount Disk 69888" issue?

There are numerous ways to fix this error message on macOS, and before diving into the six solutions mentioned below, we offer a video to assist you. Here's a summary of the video's main content:

• 00:14 - Press the Erase button
• 00:24 - Press OK to proceed due to an unsuccessful erasure
• 01:14 - Enter the command diskutil list
• 01:58 - Enter the command diskutil unmountDisk force /dev/disk0

Note: Methods 1-3 apply to an external Mac hard drive, while methods 4-6 are for an internal one.

Fix 1: Exclude the disk from Spotlight indexing

Spotlight is a tool that indexes files on your Mac and any connected devices so you can search for them quickly. If you try to format a drive that Spotlight is indexing, you might get the error "The disk could not be unmounted." You can unmount the drive by following these steps:

Step 1: Click the Apple menu and choose System Preferences, then Spotlight.

Step 2: Click the “Privacy” tab.

Step 3: Tap the “+” button and choose the folder on your external drive.

Tap the “+” button

Step 4: Click “Choose.”

Fix 2: Remove the disk from Time Machine

If your Mac has previously used the drive for Time Machine backups, it's best to prevent Time Machine from backing up to it. Follow these steps to exclude the external drive from Time Machine:

Step 1: On macOS Monterey, open System Preferences to exclude a disk from Time Machine.

Step 2: Choose “Time Machine.”

<Step 3> You need to Control-click the Time Machine backup disk that's causing the error 69888, and choose “Stop Backing Up to (Disk Name).”

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Fix 3: Force Unmount the Disk via Terminal

If you can't unmount the disk on Mac, then you can force unmount the disk in the Mac Terminal. After that, try formatting or deleting the external hard drive again. Here are the steps to force unmount a disk using Terminal:

Step 1: Open the Utilities folder from within the Applications folder.

Open Terminal from Disk Utility

Step 2: Enter the command diskutil list to get the disk identifier.

Step 3. To force the disk to unmount, type the command diskutil unmountDisk force /dev/disk and press “Enter.”

Solution 4: Fix Error 69888 using macOS Recovery If none of the above methods work, you can try fixing Error 69888 using macOS Recovery. Follow these steps: 1. Shut down your Mac. 2. Press the power button to turn it on, and immediately hold down the Command (⌘) and R keys. Keep them pressed until you see the Apple logo or a spinning globe. 3. This will boot your Mac into macOS Recovery mode. Once the system loads, you'll see a recovery window. 4. In the recovery window, click "Utilities" > "Terminal." 5. In Terminal, type the following command and press Enter: ``` csrutil disable ``` 6. The system will prompt you for confirmation. Type "y" and press Enter. 7. Restart your Mac. It will now start in non-safe mode, which may temporarily disable some system protection features. 8. Attempt to install the update again or perform the action that caused Error 69888. 9. If the installation is successful, you might need to re-enable System Integrity Protection. To do this, return to the Recovery Mode Terminal by following the steps above and enter: ``` csrutil enable ``` 10. Restart your Mac once more. Please note that disabling System Integrity Protection can make your Mac more vulnerable to malware attacks. Therefore, re-enable this feature as soon as the issue is resolved.

If you can't unmount Disk 69888 while adjusting the internal HDD volume on your Mac, these are your best solutions. In rare cases, the disk might be deleted. The “Can't unmount disk 69888” issue appears when you attempt to change the startup drive.

But because this is where the operating system starts up from, you can't format it. To work around this issue, build your computer from a different volume than the one you want to format. To resolve issue 69888, follow these steps to start your Mac in Recovery mode:

Step 1: On a newer Mac with a recovery partition, start up in macOS Recovery.

If you can't erase the Mac startup disk in Recovery Mode instead of just erasing a volume, wipe the entire drive.

Select “Show All Devices.”

Data recovery software lets you recover data from your Mac while in macOS Recovery mode. If you need to recover data, read on.

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Solution 5: Delete the Internal Drive in Safe Mode

You must be able to delete or remove other internal volumes, except for the internal drive and the “Macintosh HD - Data” volume, during a standard startup. If Disk Utility shows a “Can't unmount disk” warning before you try, restart in Mac Safe Mode, then try again.

When deleting internal volumes in safe mode, you might encounter data loss. To avoid the hassle of data loss, the all-in-one solution, Data Recovery Wizard for Mac, is here to assist you in recovering deleted files from Mac Trash.

It assists in resolving several major data loss scenarios and helps recover photos, documents, videos, emails, etc. from an internal hard drive not mounting on Mac. The best features of the Data Recovery Wizard for Mac tool are:

• Recover Empty Mac Trash
• Flexible scanning modes: Quick and Detailed.
• Preview before Recovery.
• Supports recovery from formatted/lost Mac partitions.

Download this data-recovery tool, and, with a few clicks, you can recover accidentally deleted files by following these steps:

Step 1: In the main window of Data Recovery Wizard, all the drives connected to your Mac will be listed. Select the drive from which you wish to recover deleted files and click on the 'Search Lost Files' button.

Step 2. The software will immediately scan the selected disk volume and display the scanning results in the left pane. If you're looking for certain files, you can sort the results to locate the files you need.

Step 3: Preview the files you want and then click “Recover” to start retrieving your deleted or lost Mac files.

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Unmount each volume to unmount the disk.

If you see an error message like "Disk0 unmount failed: At least one disk could not be unmounted" when attempting to install the bootable disk in Terminal, you can also delete all partitions or disks before installing the bootable disk. Follow these steps:

Step 1: Restart your Mac in Internet Recovery mode.

Step 2: Choose “Utilities” and then “Terminal.”

3. To see all connected disks and volumes, run the diskutil list command.

Run the following command:

<Step 4> Note the identifier of the disk or volume (e.g., disk1). If you have multiple drives or volumes connected to the same disk, use the command diskutil unmountDisk force /dev/disk_identifier to force it to unmount.

5. After you unmount the startup disk in Disk Utility, you can use this command in Terminal to delete the disk: diskutil eraseDisk file_system disk_name /dev/disk_identifier.

How to Resolve the "Disk Cannot Be Unmounted Error 69888"

How do I fix the "Error 69888: Cannot unmount disk" issue? Here are some top recommendations:

Restarting the Finder can fix error 69888.

The process that usually prevents a disk from being ejected is “Finder.” You need to restart Finder to stop it accessing the drive:

The first step is to right-click on the Finder icon while holding down the “Option” key.

Step 2: Click “Relaunch” to restart the Finder.

Step 3: Safely eject the external drive from your MacBook.

Step 4: You need to plug the external hard drive back into your MacBook

Step 5: Keep trying until it deletes or formats the disk.

? Quitting applications/processes using the disk

If relaunching the Finder doesn't help, you can identify which process is using the hard drive or its volume by its Process ID (PID), and kill it. The error message should clue you in to what you need to fix first. Once you have the PID of the troublesome process, follow these steps to quit it:

Step 1: Open the Terminal from the Utilities folder within Applications.

Step 2. Type the command sudo kill PID and press “Enter.”

Step 3: Type your password and press “Enter.”

Step 4 Forcefully terminate the program by entering the command sudo kill -9 PID.

Ensure the same file system before merging two partitions

If you encounter an “error: -69888: Can't unmount disk” error when attempting to merge two partitions with different formats, you must choose which file system you want to use, and reformat each partition with it before you can merge them.

For example, if one is formatted as APFS and the other as Mac OS Extended (HFS+), you would need to reformat the Mac OS Extended disk to APFS before being able to merge the two volumes.

Conclusions

While it's not common to be unable to eject a disk on macOS, the operating system is usually good at preventing issues like this. However, you may still encounter the problem when using Disk Utility to repair, format, or partition startup drives.

Next time you encounter the “Error 69888: Can't unmount disk” issue, use the above solutions. Also, to avoid data loss during the process, Data Recovery Wizard for Mac is the best recovery software!

"Frequently Asked Questions about 'Unable to Unmount Disk 69888'"

Please refer to the following FAQ to avoid the "Cannot Unmount Disk 69888" error:

1. How to Fix Error Code 69888 on Mac?

You can create a non-APFS partition before you erase the disk. Follow these steps:

Step 1: Your Mac starts up in macOS Recovery.

Step 2: Choose Disk Utility.

Step 3: Select the boot disk container.

Step 4. After selecting the partition, click the “+” button. Use any system that supports files but not APFS.

Step 5: Choose any size you need, and then click "Apply" to format the disk.

How do I force my Mac to eject a disk?

To force-eject an external hard drive on a Mac, select the disk group you want to eject in the sidebar of Disk Utility on your Mac. Choose the “Eject” option from the toolbar or next to the volume title. The disk member you want to eject must be disconnected.

Why can't I uninstall Boot Camp on my Mac?

Make sure your Mac and the external hard drive are connected properly. Unplug and plug back in the USB cable or adapter for the hard drive to ensure it's seated securely. Try connecting the hard drive to a different USB port on your Mac or to another Mac altogether. If you notice any damaged USB cables or adapters, have them repaired.

How do I eject a hard drive on a Mac? On a Mac, "ejecting a hard drive" means safely removing an external hard drive or disk volume from the system to ensure data integrity and prevent potential data loss. Here's how to do it using Finder: 1. Open Finder. 2. In the left sidebar, select "Devices" or "External Disks." 3. Locate the hard drive you want to eject. 4. Right-click on the drive icon and choose "Eject [Drive Name]." 5. The drive's icon will disappear from the Finder sidebar, indicating that it has been safely ejected. Alternatively, you can use the "File" menu in Safari or other applications to eject an open disk if you've downloaded files to an external drive. Just go to "File" > "Eject [Drive Name]". Make sure not to physically disconnect the USB cable or power off the drive until you're certain it has been safely ejected, as doing so may damage your data.

First, disconnect the optical or disk drive from the computer. When a user selects “eject” to remove a disc from a computer, the operating system unmounts the media. Unlike mounting, unmounting means taking a tape or disk cartridge out of the drive.