“Could not Modify Partition Map” Error on Mac and The way to Repair It

couldn't modify partition map

In the event you’re working with a drive and you retain getting the “Couldn’t Modify Partition Map” error, that usually means the storage gadget acquired corrupted or one thing went incorrect with the file system. This makes the complete gadget unreadable to all however very particular software program.

On this article, we discover 3 ways to cope with this error. We included step-by-step directions in addition to accompanying screenshots so you’ll be able to safely work in your drive with out worrying about your recordsdata (extra on this later). Learn on!

What’s a Partition Map?

A “partition” is a phase (referred to as a “area”) in a disk that’s handled as a person storage unit. A disk can have a number of partitions that present up as particular person storage models when related to a pc – even when, bodily, it’s only a single disk.

A “partition map” defines how partitions are organized on a disk. It incorporates essential details about the quantity. So when it will get corrupted by a virus assault or an influence surge, for instance, it turns into unreadable.

The way to Get well Deleted Information from a Problematic Machine

Due to the character of quantity and partition corruption, the answer to this downside often consists of erasing information. There’s simply no means round it. You probably have necessary recordsdata in your drive or partition, recuperate your information first. An excellent easy means to do that is by utilizing a knowledge restoration device like Disk Drill. Even when your working system can’t learn your quantity – Disk Drill can.

Disk Drill is a paid device – nonetheless, you’ll be able to preview limitless recordsdata totally free (even movies). That is necessary as a result of in the event you discover that even restoration software program can’t save your information, your drive may be bodily broken. Any additional restoration try can worsen the issue and delete your information perpetually. On this case, you’ll need to ship your drive to knowledgeable information restoration heart.

  1. Obtain the free Mac model of Disk Drill from the Cleverfiles web site and set up it.
  2. Join your gadget to your Mac.
  3. Open Disk Drill and choose the problematic USB, SD card, or drive.
    disk drill drive selection menu
  4. On the correct sidebar, you’ll be able to select what kind of scan you need to activate. For this process, we’ll use All restoration strategies.
    disk drill all recovery methods
  5. Click on the “Seek for misplaced information” button.
    search for lost data
  6. Let Disk Drill full its scanning course of. You may also use this menu to begin going via recovered recordsdata by kind, and you’ll even overview a misplaced partition particularly. For this text, we’ll click on the “Evaluation discovered gadgets” button on the backside proper nook of the window so we will look via all recovered recordsdata.
    disk drill file type menu
  7. You’ll be able to preview as many recordsdata as you need. Simply click on on the file for its preview to seem on the correct sidebar. When you’ve chosen the recordsdata you need to recuperate, click on the “Get well” button.
    disk drill recoverable files menu
  8. You’ll be greeted by a pop-up. Utilizing the dropdown menu, choose the vacation spot folder on your recovered recordsdata. Be sure you select a folder apart from the affected drive. Click on the “OK” button. Congratulations, you’ve efficiently recovered your information out of your SD card, USB, or exhausting drive!
    choose the destination folder

The way to Repair “Couldn’t modify partition map” Error

Methodology #1: Use Disk Utility’s First Support Function

In the event you encounter the error “Couldn’t modify partition map” in your SD card or flash drive, the very first thing you’ll be able to attempt is Mac’s built-in First Support characteristic inside the Disk Utility app. First Support can test and restore file system errors, which may remedy minor points earlier than they grow to be greater issues.

  1. Open Disk Utility by utilizing Highlight Search (CMD + House) or by opening Finder > Purposes > Utilities > Disk Utility app.
    utilities folder within applications folder
  2. Choose the problematic drive.
    disk utility window
  3. On the highest proper nook of the Disk Utility window, click on the “First Support” button.
    first aid button

Methodology #2: Use Disk Utility to Format the Drive and Create a New Partition Map

For this methodology, we’ll once more be utilizing Disk Utility. If First Support didn’t work, we will use the app to reformat the gadget – this may inevitably delete your information. Be sure that to conduct a restoration beforehand!  Formatting a tool will will let you create a brand new partition map for a very new partition.

  1. Open Disk Utility by utilizing Highlight Search (CMD + House) or by opening Finder > Purposes > Utilities > Disk Utility app.
    spotlight search popup
  2. Click on the “View” button on the highest left nook of the Disk Utility window and click on “Present All Units.”
    show all devices option
  3. Choose the storage gadget (not the partition) and click on the “Erase” button on the prime of the window.
    disk utility erase button
  4. Change the identify of the gadget to no matter you need, and select MS-DOS (FAT) for the format, and “Grasp Boot Document” for the scheme. Click on the “Erase” button. This overwrites the outdated partitions and creates a brand new one, together with a brand new partition map.
    partition properties and the erase button
  5. Look forward to the erase course of to finish, and click on “Performed.” You now ought to have the ability to use your gadget.

Methodology #3: Use the Terminal App to Format the Drive Create a New Partition Map

If the Disk Utility app didn’t work, you’ll be able to attempt erasing the gadget and creating a brand new partition map utilizing the Terminal app.

  1. Join your USB flash drive, SD card, or exterior exhausting drive to your Mac.
  2. Open the Terminal app by utilizing utilizing Highlight Search (CMD + House) or by opening Finder > Purposes > Utilities > Terminal app
    terminal app
  3. To seek out your Disk’s identifier, kind the next command and press return:
    diskutil listing

    terminal disk identifier

  4. When you’ve recognized your disk, kind the next command and press return:
    diskutil eraseDisk MS-DOS “disk identify” /dev/”disk identifier”
    Change “drive identify” to no matter you named your storage gadget, and “disk identifier” in accordance with the identifier you present in Step #3. For instance, right here’s what I’d kind on the Terminal app:

    diskutil eraseDisk MS-DOS SAMSUNG BAR /dev/disk4s1

If profitable, you’ll lose all of your information however it is possible for you to to make use of your gadget usually once more.



With the error “Couldn’t Modify Partition Map”, the drive is often fixable. Sadly, that usually means erasing the information saved in it. Be sure you use information restoration software program like Disk Drill beforehand if in case you have necessary recordsdata you need to salvage. Even higher, use Disk Drill and even the free Time Machine to routinely again up your recordsdata.

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