Dismounting a drive from command line does not release the drive letter

[DavidOfMA]

Expected behavior

Dismounting the drive from the command line should work the same as from the UI and release the drive letter. This is how it worked in previous versions of Veracrypt and how it still works if I dismount from the UI.

Observed behavior

When I dismount a drive using the command line (for example, "C:\Program Files\veracrypt\veracrypt.exe" /dismount J: /q), the drive letter is not released. Explorer sees it as a Local Disk, even after the drive is removed with Safely Remove.

Steps to reproduce

1. Mount an external disk drive in Veracrypt and assign it a drive letter J:
2. "C:\Program Files\veracrypt\veracrypt.exe" /dismount J:
3. The drive is dismounted but still appears as a Local Disk J: and cannot be re-assigned to J: in Veracrypt
4. Remove the drive with Safely Remove
5. The drive is still listed in Explorer as Local Disk J: but is invalid.

Screenshots

Your Environment

Windows 11 Pro, HP Laptop 17, 64GB RAM, WD external drives (various drives tried, behavior is the same in all of them)

Please tell us more about your environment

VeraCrypt version:
Veracrypt 1.26.15, 64-bit

Operating system and version:
Windows 11 Pro, 23H3, Build 22631.4169

System type:
64-bit

[amail80]

I've investigated this bug and found the root cause. Submitted a fix: #1658

Root cause: SHChangeNotify(SHCNE_DRIVEREMOVED) in BroadcastDeviceChange() is asynchronous by default. In GUI mode the process stays alive, so Explorer eventually processes the notification. In CLI mode with /q, the process exits immediately — before Explorer handles the notification. The drive letter stays in the shell namespace cache.

Fix: Add SHCNF_FLUSH flag in Silent (CLI) mode to force synchronous shell notification. Two locations: UnmountVolumeBase() in Dlgcode.c and DismountAll() in Mount.c.

This also likely fixes the older #337.

[DavidOfMA]

Great! Do you have any idea when this fix will be incorporated into a release of Veracrypt?

[amail80]

Great! Do you have any idea when this fix will be incorporated into a release of Veracrypt?

That depends on the maintainer. The PR is ready for review at #1658