Home > Questions

Disk Utility can't erase USB drive: Couldn't modify partition map

I want to reformat a USB flash drive that was previously used as a Linux boot device. When I plugged it into my Mac, I received a warning saying, "The disk you inserted was not readable by this computer." I then clicked "Initialize," which opened Disk Utility. Inside it, my disk was labeled as disk4s2. If I erase it, it fails with the error that says "Couldn't modify partition map." P.S. My thumb drive doesn't have a write-protect switch. Any idea about how I can fix it?

Best Answered by

iBoysoft author Jenny Zeng

Jenny Zeng

Answered on Monday, April 29, 2024

Instead of erasing the partition, try the physical disk.

Your external drive was a Linux boot drive, which means it has a partition map that's not readable on your Mac. Since your Mac can't modify the partition map, it can't erase the drive.

That's why you must erase the physical disk instead because it resets your drive with a compatible partition map. Follow the steps below to eliminate the "Couldn't modify partition map" error on Mac:

  1. Open Disk Utility.
  2. Click View > Show All Devices.
  3. Select the topmost level of your external drive and click Erase.
  4. Choose a name for your drive.
  5. Select a proper file system.
  6. Set the partition scheme to GUID Partition Map.
  7. Click Erase.

Did it work? If you still can't erase your USB stick on Mac, keep trying the methods in this guide:

How to Fix 'Couldn't modify partition map' on Mac (69874 & 69803)?

 

People Also Ask

Read More Questions

Read More Advice From iBoysoft's Computer Experts

Macでのテキストマルチ選択ができない

[解決済み] Mac で CMD/Shift キーを使ってテキストを複数選択できません

Mac でコマンドキーを使用してテキストを複数選択できない場合の対処法については、この記事をお読みください。この問題の原因も説明されています。

What to do if you cant save to external hard drive on Mac

Can't Save/Write to External Hard Drive on Mac (7 Solutions)

This article explains the reasons why you can't save or write to an external hard drive on Mac and offers 7 solutions to resolve it.

How to Tips

Macで外付けハードドライブの名前を変更する方法

修正しました!Macで外付けハードドライブの名前を変更できない問題

この投稿では、読み取り専用の許可、非管理アカウント、ディスクエラーなどの理由によるMacで外付けハードドライブの名前を変更できない問題を修正するための証明済みの方法を提供します。