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.
• 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.
• Microsoft’s own guidance also notes “Some updates cannot be uninstalled.” WCUs like KB5035349 fall into that bucket.
  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. 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.

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Get the K780 typing in Windows again​

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).

1. 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.

1. 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”.

1. 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. 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.
• 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.
  

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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?