Medium
Operating Systems
✓ Solution Verified by Community (0+ upvotes)
How to fix error error-subst-to-subst in Windows 11
ERROR_SUBST_TO_SUBST = 139
Fix based on community reports and expert analysis. Last verified: 2026-08-12
· How we verify fixes
| Error Code | error-subst-to-subst |
|---|---|
| Affected System | Windows 11 (Microsoft) |
| Difficulty | Medium |
| Estimated Time | 5 min |
Solution Steps
- 1 Press Windows key + R, type 'cmd', and press Enter (or Ctrl+Shift+Enter for admin). This opens Command Prompt.
- 2 Type 'subst' and press Enter. This lists all current virtual drive mappings. Look for any drive letter that is already assigned to the folder you're trying to substitute.
-
3
If you find a conflicting mapping, remove it with 'subst
: /d' (e.g., 'subst Z: /d'). This deletes the existing substitution. -
4
Now you can create the new substitution with 'subst
: ' (e.g., 'subst Y: C:\MyFolder'). Make sure the drive letter is not already in use. - 5 Verify the new mapping works by accessing the drive letter in File Explorer.
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