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[Solved] Mac mini M4 Pro encountering External Display Flickering at High Refresh Rates after update (macOS Sonoma 14.7)

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Home › Forums › MacBook, iMac & macOS Lab › [Solved] Mac mini M4 Pro encountering External Display Flickering at High Refresh Rates after update (macOS Sonoma 14.7)

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  • November 14, 2026 at 10:55 pm #13985
    Roger Fischer
    Community Contributor
    Diagnostic Hardware Specs: Mac mini M4 Pro | OS Version: macOS Sonoma 14.7 | Archive Source: Apple Support Community #256806953

    I am running into a persistent issue on my Mac mini M4 Pro running macOS Sonoma 14.7.
    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 0xf904 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?

    MacBook Air 15″ M3 (24GB) | CalDigit TS4 Dock | Kensington Orbit | Rome, IT
    Enterprise Mac Sysadmin & Jamf Pro Architect | "Verified Apple Discussions Archive"
    November 14, 2026 at 10:55 pm #13986
    Julie Sanchez
    Community Contributor
    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.

    MacBook Pro 16″ M2 Max (96GB) | Pro Display XDR | iPhone 16 Pro | Cambridge, UK
    Apple Certified Support Professional (ACSP) | iOS / Swift Engineer
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