ERROR_IS_SUBSTED 0x80070087

Error code 135 · HRESULT 0x80070087

WINDOWS

An attempt was made to use a JOIN or SUBST command on a drive that has already been substituted.

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_IS_SUBSTED is a Windows error code (system error 135, returned as HRESULT 0x80070087) reported by Windows. Its official message is: “An attempt was made to use a JOIN or SUBST command on a drive that has already been substituted.”

How to fix ERROR_IS_SUBSTED

  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_IS_JOINEDERROR_IS_JOIN_TARGETERROR_IS_SUBST_PATHERROR_IS_JOIN_PATHERROR_NOT_JOINEDERROR_NOT_SUBSTEDERROR_SEEK_ON_DEVICE

Source: Microsoft WinError.h

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