How to Fix UPERFECT C2 Pro Not Detected via USB-C on macOSUpdated 6 hours ago

Special thanks to a customer for providing a clear and highly detailed technical breakdown of this issue. Their real-world troubleshooting helped identify a reproducible macOS display configuration problem and a reliable fix.

If your UPERFECT UGame C2 Pro portable monitor was previously working but is no longer detected via a single USB-C connection on macOS, this guide summarizes the root cause and the verified solution.

Case Information

Product: UPERFECT UGame C2 Pro 16" Portable Monitor (2560×1600, 144Hz)
Host System: Apple MacBook Pro 16" (M1 Max, 2021)
macOS Version: Tahoe 26.2

Problem Description

The UPERFECT C2 Pro stopped being detected via a single USB-C connection after initially working correctly.

When connected directly to the MacBook Pro using a USB-C cable (power + video via DisplayPort Alt Mode), the monitor no longer received a video signal.

Symptoms

• Monitor powers on but displays "No Signal"
• macOS does not detect the display in System Settings → Displays
• USB-C connection fails to establish video signal
• Workaround requires:
  • USB-C for power
  • HDMI (via hub) for video
• Workaround limits output to 1080p / 60Hzinstead of native 2560×1600 / 144Hz

Root Cause

The issue is caused by macOS orphaning the display profile, resulting in a failure to associate the monitor with its DisplayPort Alt Mode configuration.

This is a macOS display configuration issue, not a hardware failure.

What Happened

• The monitor initially worked correctly via a single USB-C cable
• During unrelated troubleshooting, "Forget Device"was selected in System Settings
• macOS removed or corrupted the display profile associated with the C2 Pro
• Subsequent USB-C connections were not recognized
• The system failed to re-establish the DisplayPort Alt Mode link for that device

Troubleshooting Steps Attempted (Unsuccessful)

The following steps did not resolve the issue:

• SMC reset
• NVRAM / PRAM reset
• Testing different USB-C / Thunderbolt ports
• Reconnecting cables multiple times

These confirm the issue is not related to hardware, ports, or cabling.

Resolution (Verified Fix)

The issue can be resolved by forcing macOS to rebuild its display detection profiles.

Method 1: Finder

1. Open Finder
2. Press Command + Shift + G
3. Navigate to: /Library/Preferences/

4. Delete the file: com.apple.windowserver.plist

5. Empty Trash
6. Restart the Mac
7. Reconnect the monitor via USB-C

After restart, macOS will detect the monitor as a new display and re-establish the connection.

Method 2: Terminal

sudo rm /Library/Preferences/com.apple.windowserver.plist
sudo killall -HUP WindowServer

Why This Works

Deleting com.apple.windowserver.plist forces macOS to:

• Reset all display configuration data
• Rebuild display detection profiles
• Reinitialize DisplayPort Alt Mode mapping

This allows the system to recognize the monitor again correctly.

Post-Resolution Configuration

After the monitor is detected:

• Open System Settings → Displays
• Select the appropriate color profile
• Enable Variable Refresh Rate (VRR)to restore 144Hz
• Confirm that a single USB-C cable provides both power and video

Known Triggers

This issue may occur after:

• Using "Forget Device"in System Settings
• macOS updates affecting display settings
• Display configuration or arrangement changes
• Switching between hub-based and direct USB-C connections

Important Note

This failure mode presents as a hardware issue but is entirely software-related.

• Monitor: functioning normally
• USB-C cable: functioning normally
• Ports: functioning normally

No hardware replacement is required.

Summary