Issue Description
An external monitor is connected but macOS does not detect or display it.
Common Causes
- Incorrect cable or adapter
- Display settings misconfigured
- macOS display cache issues
Step-by-Step Solution
Step 1: Check Cable and Adapter
- Use Apple-recommended USB-C / HDMI / DisplayPort adapters
- Avoid low-quality hubs
- Test with another cable if possible
Step 2: Force Display Detection
- Open System Settings → Displays
- Hold Option key
- Click Detect Displays
Step 3: Check Display Arrangement
- System Settings → Displays → Arrangement
- Ensure displays are not mirrored incorrectly
Step 4: Restart with Monitor Connected
- Shut down Mac
- Connect monitor
- Power on Mac
Explore Further
- Reset NVRAM (Intel Macs)
Prevention & Best Practices
Use certified adapters for best compatibility.