The volume does not contain a recognised file system

If your Mac displays the message "The volume does not contain a recognized file system" when you connect your WD My Passport external hard drive, it means that macOS cannot interpret the file system currently on the drive. This issue can happen for several reasons and may involve either file system incompatibility or disk corruption. Here’s a detailed explanation and step-by-step guide (approximately 500 words) to help you understand the problem and fix it.

What This Error Means

The message usually appears when:

The drive is formatted in a file system that macOS doesn't support (like Ext4 for Linux).

The drive is corrupted and its file system structure is unreadable.

The partition table is damaged or missing.

There is a hardware issue with the drive or cable.

This is common when moving a drive between operating systems, especially from Windows (NTFS) or Linux (Ext3/Ext4) to macOS, or if the drive has become corrupted due to improper ejection or power loss.

Step-by-Step Troubleshooting Guide

1. Check Disk Utility

Go to Applications > Utilities > Disk Utility.

If the drive appears under External:

See if it shows a name and capacity.

If the Mount button is grayed out, macOS can't mount the file system.

2. Try First Aid

Select the drive in Disk Utility.

Click First Aid and run it.

If First Aid fails or gives an error, the file system is likely too damaged or unsupported.

3. Check System Information

Go to Apple Menu > About This Mac > System Report > USB.

Look for the external drive under the USB device tree.

If it shows up here, the hardware connection is okay.

If not, the problem could be the cable, port, or the drive itself.

Recovery Options

A. If You Need the Data (Don’t Format Yet)

If the drive contains important files:

Do not erase or format yet.

Use data recovery software compatible with macOS, such as:

Disk Drill

EaseUS Data Recovery Wizard

PhotoRec/TestDisk (free, but more technical)

These can often recover files from damaged or unsupported file systems.

Alternatively, if the drive was originally used on Windows:

Try accessing it again on a Windows PC.

Use CHKDSK or Windows Disk Management to check for damage.

B. If You Don’t Need the Data (Safe to Format)

If you're okay with erasing the drive:

Open Disk Utility.

Select the entire external drive (not just the volume).

Click Erase.

Format: Choose exFAT (compatible with Mac and Windows).

Scheme: GUID Partition Map.

Click Erase to reformat.

After this, the drive should mount and work normally on macOS.

Preventing Future Issues

Always eject the drive properly before unplugging it.

Avoid using the same drive across multiple systems without compatible file systems like exFAT.

Regularly back up important data to avoid loss from corruption.

If you tell me the original operating system the drive was used with (Windows, Linux, etc.), I can give more tailored recovery or formatting steps.