The released macOS Catalina 10.15 has many easy-to-use features, for most part. But sometimes, things happen that can really turn you into trouble. One of things is when you upgrade to macOS Catalina, your external hard drive shows read-only such as WD My Passport external hard drive suddenly becomes read-only on Mac. This problem is caused by various reasons, so here we will analyze some common causes and offer three feasible solutions.
1. External hard drive is formatted to NTFS.
In most cases, this happens if you are switching the external hard drive between Mac and Windows. It is because the external hard drive is formatted to NTFS for Windows. By default, macOS Catalina only enables NTFS read support, but disables NTFS write support. You check the information in Disk Utility.
Solution: Install NTFS for macOS Catalina
iBoysoft NTFS for Mac is a comprehensive NTFS for Mac program in the market to enable you easily to read, write, edit, delete, copy files from NTFS drives on macOS Catalina 10.15.
Besides, iBoysoft NTFS for Mac offers complete NTFS for Mac solutions in Catalina 10.15/Mojave 10.14/High Sierra 10.13/Sierra 10.12 and Mac OS X El Capitan 10.11/Yosemite 10.10/Mavericks 10.9/Mountain Lion 10.8. It enables you to unmount, eject, erase and repair the NTFS volumes. Also, it can list and open all attached external drives like USB flash drives, SD cards, external hard drives, etc. If necessary, you can reformat other file systems to NTFS with iBoysoft NTFS for Mac as well.
Tutorial to write to NTFS external hard drive on macOS Catalina with iBoysoft NTFS for Mac
Step 1: Download and install iBoysoft NTFS for Mac on Mac running macOS Catalina.
Step 2: Launch iBoysoft NTFS for Mac and connect the NTFS external hard drive to Mac.
Step 3: Write to NTFS external hard drive after the drive is mounted successfully.
2. Access permission not ignore
In order to protect files for multiple users, macOS has set access permission for all files, folders as well as external drives on the system. If the access permission is set up, it will prevent access to the files on the disk or to the disk itself.
Solution: Ignore permissions on external drives in Finder
There is a setting to ignore permissions on external drives on macOS. To fix read-only external hard drive on Catalina, you can simply find the option and the external drive will be fully accessible.
Step 1: Select the external hard drive on your desktop or in the Finder sidebar, and then press Command-I to get information on the drive.
Step 2: Click on the arrow that is at the left side of the "Sharing & Permissions" tab near the bottom of the window.
Step 3: Check the box to "Ignore ownership on this volume", or toggle it off and then on if it's already enabled.
3. Check errors on the external hard drive
Some minor formatting errors will lead to read-only external hard drive. When these errors occur, to prevent further data corruption, the operating system will mount it in a read-only state.
Solution 1: Repair the external hard drive via First Aid
Step 1: Open Disk Utility.
Step 2: Select the read-only external hard drive on the left window.
Step 3: Click First Aid in the top center and choose Run.
Solution 2: Reformat the external hard drive
If Disk Utility fails to fix the read-only external hard drive, we should consider wiping the drive and repartitioning it. But if you have important data on the external hard drive, you'd better recover lost data on macOS Catalina with iBoysoft Data Recovery for Mac.