Fix Couldn't Modify Partition Map on Mac (69874 & 69803)

"Couldn't modify partition map on Mac" is a common error that occurs when partitioning, formatting, or repairing an external or internal drive on a Mac. This error usually occurs because various scenarios trigger your MacOS and lead to corruption. Corruption in the partition map OS files and a locked SD card can all lead to this error. Do not worry; this post will investigate further to find fixing methods.

First Thing to Do: Recover Lost Files After Couldn't Modify Partition Map Error

If you are eager to fix your corrupted drive using the First Aid feature in Disk Utility but the error message "Couldn't modify partition map" pops up, your files on the drive might be lost. So, before proceeding with the fixes, the first thing to do is to recover your lost files with the help of EaseUS Data Recovery Wizard for Mac.

This file recovery software for Mac helps restore deleted files from various devices and enjoys a success rate of 99.7%. This tool can also retrieve data lost in disk management errors like com.apple.DiskManagement.disenter error 49244.

Follow the steps below to perform the Mac hard drive recovery that was reported Couldn't modify partition map error:

Step 1. Search for lost files

Select the disk location to search for lost files (it can be an internal HDD/SSD or a removable storage device) on macOS Sierra, High Sierra, Mojave, Catalina, Big Sur, Monterey, Ventura, and the latest Sonoma. Click the "Search for lost files" button.

Note: Before data recovery, you'd better click "Disk Backup" from the left sidebar to create a backup of your Mac to avoid further data loss. After backing up, the software can recover data from the Mac backup, and your computer can wirte new data again.

Step 2. Go through the scanning results

EaseUS Data Recovery Wizard for Mac will immediately scan your selected disk volume and display the scanning results.

Step 3. Select the file(s) and recover

In the scan results, select the file(s) to preview and click the "Recover" button to have them back.

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Fix 1. Create a New Partition Map to Solve Cannot Modify Partition Map on Mac 

After securing your data, you can solve the problem by creating a new partition map. To create a new partition, you will force the utility to show all devices and delete the partition with the issue.

In a step-by-step guide, we will discuss two primary ways of fixing this annoying issue. Don't be left out!

1️⃣ Use Disk Utility to create another partition map:

Here is how to do it!

Step 1. Open your "Finder." 

Step 2. Click  "Utilities" > "Disk Utility."

Step 3. Select "View" and click "Show All Devices" to enable it.

Step 4.  Select the device that had an issue from the list that appears.

Step 5. Right-click on the problematic device and click "Erase." But first, ensure that you set the Scheme and Format to Master Boot Record and MS-Dos (FAT), respectively.

Step 6. After the process, stay patient while creating the new partition map.

2️⃣ Use the Terminal App to create a new partition map:

Here is how to use the Terminal application!

Step 1. Open your "Finder."

Step 2. Click "Go" > "Utilities."

Step 3. Double-click on "Terminal" to open it and type diskutil list to identify the problematic drive path.

Step 4. The list of devices will appear. Type diskutil eraseDisk ExFAT *DeviceName* /dev/disk2. Please note that DeviceName is a placeholder, not part of the command; consider replacing it with the problematic device's name.

You can confirm if the error is fixed at the end of this process.

Fix 2. Repair Disk from Recovery Mode to Solve Couldn't Modify Partition Map Error

You can also deal with system corruption by initiating the repair disk via Recovery Mode. Sometimes, the error problem is due to permission problems that can't be resolved conventionally.

Follow the steps below to repair the disk from Recovery Mode.

Step 1. Restart your Mac, and while it restarts, hold on to Command + R. Please don't let off the keys until the Apple log appears.

Step 2. In the "Utilities" menu, click "Disk Utility." You may need your password to get admin access.

Step 3. Choose the affected drive and click "First Aid" > "Run" to begin the operation.

Be patient as the utility identifies the errors for recovery. Once done, restart your Mac to see whether the issue is solved.

Fix 3. Unlock SD Card or USB Drive to Fix Couldn't Modify Partition Map on Mac

The error could be popping because your SD card is locked, and unlocking it could solve the problem. Here, you will manually unlock the disk and then retry the operation.

The issue usually occurs when using an older SD card, as finding a locked SD card nowadays is rare. If your SD card is a new one, consider checking it thoroughly, as some manufacturers lock the arrow at the switch with a label.

After checking all that, the error should be gone, and if not, you will rule out this point as the problem.

Conclusion 

The inability to modify the partition map is a standard error for MacOS users, but it can be solved once you identify the cause. You can solve the problem by unlocking your SD,  creating a new partition map, and initiating disk repair. Apart from trying all the fixes, you can secure your data using the EaseUS Data Recovery Wizard for Mac. Install this faster and all-in-one software to get started with the process.

FAQs on Couldn't Modify Partition Map on Mac

Use the following question to get more information regarding the error code on Mac.

1. What is error code 69874 on Mac?

When formatting or partitioning, receiving the error couldn't modify the partition map is expected. It occurs when the system fails to verify a particular file. However, you can identify the cause and solve it.

2. How do I fix the partition map on my Mac?

Use First Aid to fix the partition map on Mac. MacOS devices have this inbuilt feature.

This is how to do it!

Step 1.  Go to "Finder" > "Applications."

Step 2. Select "Utilities" > "Disk Utility."

Step 3. Select the affected drive and click "First Aid" > "Run" to begin the operation

3. Why can't I modify the partition map on the SD card?

SD cards contain physicals that may prevent you from modifying the partition map. Therefore, you may need to deactivate the locks and allow write protect to save yourself from receiving the error couldn't modify partition map when using Disk Utility.

Moreover, check your SD card for any issue that prevents you from modifying the partition map.