File Locksmith

Identify which processes are using a file or folder and end those processes

Overview

File Locksmith helps you discover which processes are locking a file or folder, preventing deletion, moving, or modification. It integrates directly into File Explorer’s context menu, allowing you to quickly identify and terminate locking processes.

Terminating processes may result in data loss. Always save your work before ending processes.

Activation

1. Enable File Locksmith

   Open PowerToys Settings and enable File Locksmith

2. Right-Click File/Folder

   In File Explorer, right-click on a locked file or folder

3. Select 'What's using this file?'

   Choose the File Locksmith option from the context menu

4. View Locking Processes

   A window appears showing all processes using the file

Key Features

Process Detection

File Handle Detection

Identifies processes with open file handles

Shows read/write access modes

Folder Monitoring

Detects processes accessing folders

Includes files within directories

Multiple Files

Check multiple files simultaneously

Select multiple files in Explorer

Process Details

Shows process name, PID, and user

Full path to executable

Context Menu Integration

Seamless File Explorer integration:

// Explorer command registration
class FileLocksmithContextMenu : public IExplorerCommand
{
public:
    // Display in context menu
    HRESULT GetTitle(IShellItemArray* items, LPWSTR* name)
    {
        *name = L"What's using this file?";
        return S_OK;
    }
    
    // Handle menu item click
    HRESULT Invoke(
        IShellItemArray* selection,
        IBindCtx* bindContext
    );
};

Menu location:

• Right-click file/folder
• “Show more options” (Windows 11)
• “What’s using this file?” option

Process Information Display

Detailed information about locking processes:

• Process Name: Application name
• Process ID (PID): Unique process identifier
• User: Account running the process
• File Path: Full path to executable
• Access Type: Read, Write, or Read/Write
• Handle Count: Number of open handles

Process Termination

End Process

Gracefully terminate a process:

1. Select process in File Locksmith window
2. Click “End Process” button
3. Confirm termination
4. Process receives termination signal
5. File/folder is unlocked

Note: Similar to Task Manager’s “End Task”

End Process Tree

Terminate process and all child processes:

• Useful for parent processes with children
• Ensures complete cleanup
• Recommended for stuck applications

Example: Ending Visual Studio also ends MSBuild and compiler processes

Force Terminate

Forcefully kill unresponsive processes:

• Last resort option
• No cleanup or save opportunity
• Use when graceful termination fails

Warning: May cause data loss

Configuration

Settings

Minimal configuration required:

enabled · boolean · default: "false"

Enable or disable File Locksmith

Controls context menu integration

extended_context_menu · boolean · default: "false"

Show in extended context menu only

Requires holding Shift while right-clicking

Extended Context Menu

Reduce context menu clutter:

• Disabled: Always visible
• Enabled: Only visible when holding Shift

Windows 11 note: File Locksmith appears under “Show more options” by default

Use Cases

File Deletion Issues

Cannot delete file

Common scenario:

Error: The action can't be completed because
the file is open in another program

Solution:

1. Right-click file → “What’s using this file?”
2. Identify locking process
3. Save work in that application
4. End process
5. Delete file successfully

File in use after closing app

Application closed but file still locked:

• Background process still running
• Crash left handles open
• Service holding file

Use File Locksmith to:

1. Find zombie process
2. Terminate lingering handles
3. Clean up properly

Development Scenarios

1. DLL Rebuild Issues

   Cannot rebuild project due to locked DLL:

   Error: Cannot copy 'MyLibrary.dll' because
   it is being used by another process
   

   Identify: Test application still running

2. Log File Access

   Cannot delete or move log files:

   • Application still logging
   • Log viewer has file open
   • Background service writing logs

   Find: Which process is logging

3. Database Files

   Database file locked:

   • SQLite .db file in use
   • Multiple connections open
   • Crashed application

   Solution: End all database connections

System Maintenance

Folder Deletion

Cannot delete folder with locked files

Find all processes using folder contents

USB Drive Ejection

“Device is in use” error

Identify processes accessing USB drive

File Moving

Cannot move files between folders

Discover hidden locks

Update Installations

Installer cannot replace files

End processes before updating

Media Production

Video Editing

Video file locked by:

• Video player in background
• Encoder still processing
• Preview generator

Use File Locksmith to find and close

Audio Production

Audio file locked by:

• DAW (Digital Audio Workstation)
• Media player
• Audio driver/service

Identify locking application

Image Editing

Image file locked by:

• Photo editor
• Thumbnail generator
• Image viewer

Terminate background processes

Network Shares

Files on network drives:

Scenario: Shared folder file locked

File: \\Server\Share\Document.docx
Issue: "File is in use by another user"

File Locksmith shows:
  - Remote user's process
  - Network session details
  - Cannot terminate remote process
  
Solution:
  - Contact user to close file
  - Administrator can force-close from server

Technical Details

Architecture

Handle Detection

File Locksmith uses Windows APIs to enumerate handles:

// Handle enumeration
NTSTATUS NtQuerySystemInformation(
    SYSTEM_INFORMATION_CLASS SystemInformationClass,
    PVOID SystemInformation,
    ULONG SystemInformationLength,
    PULONG ReturnLength
);

// Query handle information
NTSTATUS NtQueryObject(
    HANDLE Handle,
    OBJECT_INFORMATION_CLASS ObjectInformationClass,
    PVOID ObjectInformation,
    ULONG ObjectInformationLength,
    PULONG ReturnLength
);

Process:

1. Enumerate all system handles
2. Filter handles of type “File”
3. Query handle name/path
4. Match against target file
5. Return owning process information

Components

Component	Purpose	Location
FileLocksmithCLI	Command-line interface	src/modules/FileLocksmith/FileLocksmithCLI
FileLocksmithContextMenu	Explorer integration	src/modules/FileLocksmith/FileLocksmithContextMenu
FileLocksmithLib	Core handle detection	src/modules/FileLocksmith/FileLocksmithLib
FileLocksmithUI	User interface	src/modules/FileLocksmith/FileLocksmithUI

CLI Usage

File Locksmith can be used from command line:

# Check what's using a file
FileLocksmith.exe "C:\Path\To\File.txt"

# Output: List of processes with PIDs
# Process: notepad.exe (PID: 1234)
# User: DOMAIN\Username
# Path: C:\Windows\System32\notepad.exe

Source: src/modules/FileLocksmith/FileLocksmithCLI/main.cpp

Process Termination

Multiple termination methods:

// Graceful termination
bool TerminateProcess(DWORD processId)
{
    HANDLE hProcess = OpenProcess(
        PROCESS_TERMINATE, 
        FALSE, 
        processId
    );
    
    if (hProcess)
    {
        // Send termination signal
        BOOL result = ::TerminateProcess(hProcess, 0);
        CloseHandle(hProcess);
        return result;
    }
    return false;
}

// Process tree termination
void TerminateProcessTree(DWORD processId)
{
    // Find child processes
    auto children = GetChildProcesses(processId);
    
    // Terminate children first
    for (auto child : children)
    {
        TerminateProcessTree(child);
    }
    
    // Terminate parent
    TerminateProcess(processId);
}

Keyboard Shortcuts

In File Locksmith Window

Shortcut	Action
Shift+Right-Click	Show context menu (if extended menu enabled)
Enter	End selected process
Delete	End selected process
Esc	Close window
F5	Refresh process list

Troubleshooting

Context menu option not appearing

Check:

• File Locksmith is enabled in PowerToys Settings
• On Windows 11, check under “Show more options”
• If extended menu enabled, hold Shift while right-clicking

Fix:

1. Restart File Explorer
2. Disable and re-enable File Locksmith
3. Restart PowerToys
4. Check shell extension registration

No processes shown but file is locked

Possible causes:

• System/kernel process holding file
• File locked by Windows itself
• Network share lock (remote process)
• Permissions prevent detection

Solutions:

1. Run PowerToys as Administrator
2. Check Windows Event Viewer for file access logs
3. Use Process Explorer for deeper analysis
4. Restart computer to clear all locks

Cannot end process

Reasons:

• Insufficient privileges (need admin)
• System-critical process
• Process already terminating
• Protected process

Try:

1. Run PowerToys as Administrator
2. Use “End Process Tree” option
3. Use Task Manager with admin rights
4. Restart computer

Protected processes: Cannot be terminated (e.g., csrss.exe, System)

File still locked after ending process

Check:

• Process actually terminated (check Task Manager)
• File handle cleanup may take a moment
• Another process opened file
• File system sync delay

Steps:

1. Wait a few seconds
2. Re-run File Locksmith
3. Check for additional locking processes
4. Refresh File Explorer (F5)

Limitations

Cannot terminate remote processes:

For files on network shares, File Locksmith shows which remote computer/user has the file open but cannot terminate processes on remote machines.

Workaround: Administrator must close file from server side or use server management tools.

Kernel-Mode Locks

Some file locks are held by kernel drivers:

• Antivirus scanners
• File system filters
• Disk encryption software
• Backup agents

These may not appear in File Locksmith’s process list.

Permission Requirements

To terminate processes:

• User processes: No special permissions
• Other users’ processes: Administrator rights
• System processes: Administrator + may be protected
• Services: Administrator + service control rights

See Also

• File Explorer Add-ons - Preview file contents
• PowerToys Run - Quick file search
• Process Explorer - Advanced process analysis (Sysinternals)