ERROR_SEM_IS_SET 0x80070066

Error code 102 · HRESULT 0x80070066

WINDOWS

The semaphore is set and cannot be closed.

Windows troubleshooting diagram: Device Manager warning and a system file scan
Windows errors: check drivers, system files and Event Viewer, in that order.

What it means

ERROR_SEM_IS_SET is a Windows error code (system error 102, returned as HRESULT 0x80070066) reported by Windows. Its official message is: “The semaphore is set and cannot be closed.”

How to fix ERROR_SEM_IS_SET

  1. Reboot once — many one-off system codes disappear with a clean restart
  2. Repair system files: 'sfc /scannow' then 'DISM /Online /Cleanup-Image /RestoreHealth'
  3. Find the source in Event Viewer → System: filter for this exact code and open its provider link

Related errors

ERROR_SEM_TIMEOUTERROR_SEM_OWNER_DIEDERROR_SEM_USER_LIMITERROR_SEM_NOT_FOUNDERROR_INVALID_PARAMETERERROR_EXCL_SEM_ALREADY_OWNEDERROR_TOO_MANY_SEM_REQUESTS

Source: Microsoft WinError.h

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