Fix Couldn't Open Device 69877 on Mac in 4 Ways [Keep Your Data Safe]

You may receive Error: -69877: Couldn't open device in Terminal or Couldn't open device.: (-69877) in Disk Utility when you try to erase the whole disk on a Mac. This post will guide you through solving this disk error and restoring essential data on a disk that couldn't be opened on a Mac.

The "Error: -69877: Couldn't open device" on a Mac typically indicates an issue when attempting to erase or format a disk, including USB drives, SD cards, and internal HDDs, particularly when the disk is not recognized or has write protection.

You may receive "Couldn't open device.: (-69877)" in Disk Utility or "Error: -69877: Couldn't open device" in Terminal when you try to erase the whole disk on a Mac.

Suppose the stored data is not so important to you, or you have advanced backups. Fully erasing a Mac using Recovery Assistant helps solve the error 69877. However, you should note that this option will delete all data on your Mac. Therefore, if you want to restore data from the disk, read on! This post will guide you through solving this disk error and restoring essential data on a disk that couldn't be opened on a Mac.

Why "Error -69877: Couldn't Open Disk" Occurs

M-series (Apple Silicon) Macs don't allow you to erase the whole disk because they host two system-critical containers hidden from the Disk Utility sidebar to help protect you from damaging your system. So if you try to erase the whole disk, "Error 69877: Couldn't open device" may appear in Disk Utility.

Besides, here are some other possible causes why the error 69877 occurs:

⛔Permission issue: The external hard drive (USB flash drive or SD card) may enable write protection to prevent its data from changing. Therefore, you may not have permission to write on the hard drive.

🔑Encryption issue: This disk may enable its encryption option, such as FileVault, preventing the disk from being written to.

💻Software glitch: Your Mac may be unable to access the disk due to software glitches, or macOS may identify the hard drive as problematic by mistake.

You can't see files on an external hard drive if "Couldn't open device.: (-69877)" shows up when inserting it. Restoring the stored files on the problematic disk is essential in this case. You can install Mac data recovery software to perform Mac hard drive recovery and save all your data quickly in only three steps, without any technical requirements.

After saving all your essential files on the hard drive, here are four effective methods you can refer to:

Fix Permission Issue to Solve "Couldn't Open Device 69877"

Here are the steps to check the disk permission on a Mac:

Step 1. Select it and press the "Command" and "I" keys to display the Get Info window when the disk is connected to your Mac and mounted in the Finder.

Step 2. Scroll to the bottom of the window and look for the "Sharing & Permissions" section. If it's not visible, click the drop-down arrow to view it.

Step 3. Under the Sharing & Permissions heading, it should tell you what access you have:

• You can read and write
• You have custom access 

If not, click the "Privilege" column opposite your username and change the privileges to "Read and write".

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Decrypt the Disk to Solve "Error: -69877: Couldn't Open Device"

This method only works when you insert an external hard drive into your Mac. It may be encrypted on a Windows PC, including a BitLocker encrypted disk, so you can't read or write it on a Mac. In this case, you should decrypt the disk first and then plug it into your Mac.

Run First Aid to Repair the Corrupted Disk with Error 69877

A corrupted disk may also bring some errors when working on a Mac. Running the "First Aid" helps solve the disk error so your Mac can read and write the disk normally.

Step 1. Launch "Disk Utility" and select the disk with error 69877.

Step 2. Click the "First Aid" button at the top menu, and hit "Run".

Use Erase All Content and Settings to Fix Disk Error 69877

Install EaseUS Data Recovery Wizard for Mac to save your files before erasing all content and settings:

Step 1. Select the location to scan

Launch EaseUS Data Recovery Wizard for Mac and choose the hard drive, SSD,  SD card, USB flash drive, or TF card where you lost data. Click "Search for lost files" to start scanning.

Step 2. Filter lost Mac data

The software will automatically scan for lost data on MacBook/iMac. When the scan completes, filter wanted data through the "Type" and "Path" buttons.

Step 3. Recover lost data or files

Double-click a file to preview it. Then, click the "Recover" button to restore the lost data to another place. 

After saving your files, refer to the following steps to erase your Mac and solve the disk error 69877.

Step 1. Open the Apple menu and choose "System Settings > General > Transfer or Reset".

Step 2. You will see two buttons in this window, and choose "Erase All Content and Settings".

Conclusion

If you received the "Error: -69877: Couldn't open device" or "Couldn't open device.: (-69877)" in Disk Utility when you try to erase the whole disk on a Mac. This post discusses how to solve this disk error and restore essential data via the trusted Mac data recovery tool - EaseUS Data Recovery Wizard.

Couldn't Open Device 69877 FAQs

Here are questions people frequently ask about how to fix "Couldn't open device.: (-69877)" on a Mac:

1. How to fix erase Mac couldn't open device 69877?

M-series (Apple Silicon) Macs don't allow you to erase the whole disk because they host two system-critical containers hidden from the Disk Utility sidebar to help protect you from damaging your system. So if you try to erase the whole disk, "Error 69877: Couldn't open device" may appear in Disk Utility. To fix this error, you can erase all content and settings on your Mac.

2. How do I fix a couldn't unmount disk 69888 error on my Mac?

The "couldn't unmount disk 69888" error on Mac may be due to a non-APFS partition. Follow the steps below:

Step 1. Start up your Mac in macOS Recovery.

Step 2. Select "Disk Utility".

Step 3. Choose the startup disk container.

Step 4. Hit the (+) button after selecting the partition. Any system that supports files but not APFS should be used.

Step 5. Pick any size you want, and tap "Apply" to reformat the drive.