ERROR_DS_AUX_CLS_TEST_FAIL 0x800720C5

Error code 8389 · HRESULT 0x800720C5

WINDOWS

Schema update failed: class in aux-class list does not exist or is not an auxiliary class.

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_DS_AUX_CLS_TEST_FAIL is a Windows error code (system error 8389, returned as HRESULT 0x800720C5) reported by Windows. Its official message is: “Schema update failed: class in aux-class list does not exist or is not an auxiliary class.”

How to fix ERROR_DS_AUX_CLS_TEST_FAIL

  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_DS_NONEXISTENT_MUST_HAVEERROR_DS_NONEXISTENT_POSS_SUPERROR_DS_NONEXISTENT_MAY_HAVEERROR_DS_SUB_CLS_TEST_FAILERROR_DS_EXISTS_IN_MAY_HAVEERROR_DS_BAD_RDN_ATT_ID_SYNTAXERROR_DS_EXISTS_IN_MUST_HAVE

Source: Microsoft WinError.h

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