Experiencing issues with your computer recognizing an external hard drive after a macOS update can be attributed to several factors.
Check Physical Connections:Try using a different USB or Thunderbolt port to rule out potential port issues.
Restart Your Computer: A simple restart can often resolve glitches introduced by software updates.
Verify Disk Utility: Check if the external hard drive appears in the list. If it does, there may be a mounting or file system issue.
Update External Drive Drivers: Visit the website of the external hard drive's manufacturer and check for updated drivers or firmware that are compatible with the latest macOS version. Install any available updates.
Check System Information: Check if the external hard drive is listed.
Test on Another Mac: Connect the external hard drive to another Mac to determine if the issue is specific to your computer.
Verify File System Compatibility: macOS typically supports formats like APFS, HFS+, and ExFAT.
Reset NVRAM/PRAM: Resetting the NVRAM (Non-Volatile Random-Access Memory) or PRAM (Parameter RAM) can sometimes resolve hardware-related issues. Restart your Mac and hold down Command + Option + P + R until you hear the startup chime twice.
Contact External Drive Manufacturer: If the issue persists, reach out to the external hard drive manufacturer's support for specific guidance and troubleshooting steps related to your device.
By systematically going through these troubleshooting steps, you can identify and potentially resolve the issue of your computer not recognizing an external hard drive after a macOS update. If problems persist, contacting Apple support or the external hard drive manufacturer's support is advisable for further assistance.
Read also: Why does my computer display a 'Low Disk Space' warning