Windows 11 Logi K780 stopped working 9/16/2025

Short answer on those two KBs​

• KB5035349 is a Windows Configuration Update (WCU). WCUs show under “Other updates” and do not create a normal uninstall entry. In practice, you can’t remove them via Settings, WUSA, or DISM. They’re feature-flag/config changes Microsoft can reissue over time. (blogs.windows.com)
• KB5035942 is normally a March 26, 2024 Windows 11 preview cumulative update (LCU). LCUs can be removed only with DISM and only if that exact LCU package is present on your PC. Note: using wusa /uninstall won’t work for combined SSU+LCU packages. (support.microsoft.com)
• Microsoft’s own guidance also notes “Some updates cannot be uninstalled.” WCUs like KB5035349 fall into that bucket. (support.microsoft.com)

If you want to test whether KB5035942 (if it’s truly the LCU on your system) is removable:
1) Open Terminal (Admin) and run:
dism /online /get-packages | findstr 5035942
2) If you see a Package_for_RollupFix… entry, remove it:
dism /online /remove-package /packagename:Package_for_RollupFix~31bf3856ad364e35~amd64~~<version goes here>
3) Reboot and re‑test. If no package is found (common when it shows only under “Other updates”), DISM removal isn’t possible. (support.microsoft.com)
If this started right after Sept 16, your fastest “rollback” is System Restore to a point from 2025‑09‑15 or earlier (if available). System Restore specifically undoes recent updates/drivers without touching your files. (support.microsoft.com)

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Get the K780 typing in Windows again​

Because the keyboard works on iOS, this looks like Windows’ Bluetooth HID enumeration got stuck. Do the cleanup in this order:
1) Hard‑reset and set Windows layout on the K780

• Reset: turn the keyboard off → press Esc+O, Esc+O, Esc+B (in sequence) → turn it on; Easy‑Switch 1 should blink ready to pair.
• Force Windows layout: hold Fn+P for 3 seconds (Mac layout is Fn+O). (reddit.com)

2) Remove stale entries and re‑pair cleanly

• Settings > Bluetooth & devices: Remove every “Keyboard K780/Logitech K780/Keyboard” entry.
• Device Manager > View > Show hidden devices. Expand Bluetooth, Keyboards, and Human Interface Devices. Uninstall any greyed “Bluetooth LE…”, “HID Keyboard Device”, or K780‑named entries. Reboot, then pair again by long‑pressing your chosen Easy‑Switch key for 3 seconds until it blinks, and complete pairing from Settings. (manualsnet.com)

3) Restart the Bluetooth stack

• Services (services.msc): restart “Bluetooth Support Service”. Then toggle Bluetooth off/on in Settings. If you see your adapter in Device Manager, clear Power Management “Allow the computer to turn off this device to save power” on the Bluetooth adapter and on any “HID Keyboard Device”.

4) Try the Unifying receiver (workaround)
If you have the Logitech Unifying USB receiver, pair the K780 to it (it supports both Bluetooth and Unifying). This bypasses any BLE HID quirk introduced by a recent update. (manualslib.com)
5) Avoid third‑party driver updaters for Bluetooth
Auslogics can sometimes push mismatched BT stacks. Prefer the OEM Bluetooth driver (Intel/Realtek) or the in‑box one via Windows Update. If you recently changed BT drivers, roll back in Device Manager and retest.

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If you still need to “roll back” beyond the above​

• Latest quality update uninstall (WinRE): Settings > System > Recovery > Advanced startup > Troubleshoot > Advanced options > Uninstall Updates > Uninstall latest quality update. This only applies to LCUs, not WCUs. (support.microsoft.com)
• No restore point and uninstall not offered? An in‑place repair install with current Windows 11 media keeps your apps/files but refreshes the OS components and BT stack—often fixes stubborn Bluetooth HID issues without touching data. (support.microsoft.com)

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Can you confirm:

• Your exact Windows version/build (run winver), and whether the K780 is using Bluetooth or a Unifying receiver?
• After the reset + clean re‑pair steps above, does “HID Keyboard Device” reappear under Keyboards in Device Manager?

First, clear out the keyboard from Device Manager and Bluetooth settings, reboot, and re-pair it. Make sure the Bluetooth service is running, disable power saving on the adapter, and try the Windows Bluetooth troubleshooter. If that doesn’t work, uninstall and reinstall the Bluetooth driver (use your PC maker’s driver if possible). You can also try fixing system files with sfc /scannow and DISM. If you really need to roll back the updates, run DISM /Online /Get-Packages to find the exact package name, then use DISM /Online /Remove-Package /PackageName:<name> to uninstall. If uninstalling won’t work, pause Windows Updates, block those updates with Microsoft’s hide-updates tool, or roll back with System Restore if you’ve got a point from before 9/16.

Your playbook is solid. A few high‑leverage additions that often fix “BT keyboard dead after update” faster:

• Verify key services and power settings
  • Run services.msc and ensure Bluetooth Support Service (bthserv) is Running (Startup type: Manual/Trigger Start is fine). Also check Human Interface Device Service.
  • In Device Manager > Bluetooth adapter > Properties > Power Management, uncheck “Allow the computer to turn off this device to save power.” Do the same for HID Keyboard Device under Keyboards.
• Do a clean Bluetooth stack refresh
  1) In Settings > Bluetooth & devices, Remove the keyboard.
  2) Device Manager > View > Show hidden devices. Under “Bluetooth” and “Keyboards,” uninstall the keyboard, the Bluetooth LE Peripheral that matches it, and the Bluetooth adapter driver (check “Delete the driver software” only if you have the OEM package ready).
  3) Reboot, install the latest OEM Bluetooth driver package (prefer OEM over Windows Update), then re‑pair.
• Troubleshooter path (Windows 11)
  • Settings > System > Troubleshoot > Other troubleshooters > Bluetooth > Run.
• Quick integrity/repair set
  • Run in elevated Terminal:
    
    Code:

    DISM /Online /Cleanup-Image /RestoreHealth
    sfc /scannow

  • Reboot and test pairing again.
• If the recent cumulative update broke BT/keyboard
  • List packages, note the exact Package Identity, then remove:
    
    Code:

    DISM /Online /Get-Packages /Format:Table
    DISM /Online /Remove-Package /PackageName:<paste_full_package_identity>

    Or try:
    wusa /uninstall /kb:<KBID> /quiet /norestart
  • Immediately Pause updates (Settings > Windows Update) and hide that KB with Microsoft’s “Show or hide updates” tool to prevent re‑installation until a fixed build appears. We’ve seen users report BT/keyboard/Wi‑Fi failures tied to KB5063878 and use this exact pause/hide workflow successfully.
• When to look deeper
  • If Device Manager shows error icons on the BT adapter after re‑install, grab the OEM combo pack (Bluetooth + Wi‑Fi) and chipset drivers, then reboot. If pairing still fails, check Event Viewer > Applications and Services Logs > Microsoft > Windows > Bluetooth-* for driver errors. If this started right after a specific August 2025 cumulative (e.g., KB5063878), keep it uninstalled/hidden until Microsoft re-issues a corrected package.

If you share your laptop model, Windows build, and the KB you’re rolling back, I can link the exact OEM driver package and give you the precise package name/commands to remove and block that update cleanly.