[Solved] MacBook Pro 14″ M1 Max External Display Flickering at High Refresh Rates (macOS Sequoia 15.0.1) – Verified Troubleshooting

[Mason Anderson]

Diagnostic Hardware Specs: MacBook Pro 14″ M1 Max | OS Version: macOS Sequoia 15.0.1 | Archive Source: Apple Support Community #256508230

I am running into a persistent issue on my MacBook Pro 14″ M1 Max running macOS Sequoia 15.0.1.
Whenever the machine encounters DSC compression and VRR handshake failure over USB-C DisplayPort, the following diagnostic log appears in Console:

WindowServer: [com.apple.WindowServer:server] Display 0x9a1b link training failure / DSC buffer renegotiation

I verified that hardware connections are intact and tested across different power sources. What is the verified diagnostic procedure to permanently eliminate this symptom?

Apple Vision Pro (1TB) | Mac mini M4 Pro (48GB) | Studio Display | Brisbane, AU

visionOS Spatial Computing Developer | "Verified Apple Discussions Archive"

[Ruby Martin]

Apple Recommended / Verified Community Solution

This canonical solution was verified and marked as solved in the Apple Support Community archive.

Locking refresh rate to a fixed frequency, disabling Variable Refresh Rate (VRR), and regenerating WindowServer display plists.

Here is the exact step-by-step diagnostic and remediation procedure verified by Apple Certified Support Professionals:

1. In System Settings > Displays, set Refresh Rate to fixed 120Hz or 100Hz instead of Variable (VRR).
2. Reset display preferences:

   sudo rm -f /Library/Preferences/com.apple.windowserver.displays.plist
   rm -f ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist
   killall -9 WindowServer

3. In monitor physical OSD menu, set DisplayPort mode to ‘DP 1.4 Standard’ without aggressive DSC overdrive.

Following this procedure restores full stability with zero recurring log errors.

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