How to fix Error 137 on Windows 11

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Troubleshooting Guide: Error 137 – “System Tried to Delete the Substitution of a Drive That Is Not Substituted”

Why This Error Happens

Error 137 occurs when the system attempts to remove a virtual drive mapping created by the SUBST command, but no such substitution actually exists for that drive letter. This typically happens due to a corrupted or outdated batch script, logon script, or startup entry that references a stale SUBST mapping which was already removed, never created, or cleared after a reboot (since SUBST mappings are not persistent by default). It can also occur if a third-party application or backup tool improperly tracks virtual drive letters in its configuration and tries to unmap a drive that Windows never registered as substituted.

Step-by-Step Resolution Guide

  1. Check Current SUBST Mappings
    Open Command Prompt as Administrator and run:
   subst

This lists all currently active substituted drives. If the drive letter in question isn’t listed, it confirms no active substitution exists.

  1. Locate the Source of the SUBST Command
    Search for scripts calling SUBST in common locations:
  • C:\Windows\System32\GroupPolicy\Machine\Scripts\Startup
  • Task Scheduler (taskschd.msc) — check for tasks running subst or .bat/.cmd files.
  • Registry Run keys: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
  1. Remove or Correct the Faulty Script/Entry
    If you find a script attempting subst X: /D (delete) without first verifying the drive exists, either:
  • Delete the outdated task/script, or
  • Edit it to include a conditional check, e.g.:
    batch
    subst | find "X:" >nul && subst X: /D
  1. Recreate and Properly Remove the Substitution (if needed)
    If you intended to use a substituted drive, create it correctly first:
   subst X: C:\YourFolder

Then remove it safely:

   subst X: /D
  1. Clear Related Registry Remnants
    Check HKEY_CURRENT_USER\Network and HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2 for orphaned drive letter entries and remove any invalid ones (back up the registry first).

Alternative or Verification Steps

  • Verify the Fix: Restart your PC and check Event Viewer (eventvwr.msc → Windows Logs → System) to confirm Error 137 no longer appears after the next scheduled task or logon script runs.
  • Alternative Fix: If the error persists and the source can’t be found, disable third-party backup/sync software temporarily (many virtual drive tools misuse SUBST) and monitor whether the error recurs.