When a Windows service starts, its default working directory is always %windir%\system32 (typically C:\Windows\system32). This behavior is hardcoded into the Service Control Manager (SCM) and cannot be modified through standard service configuration.

Many services need to access configuration files, dependent assemblies, or data files stored in specific locations. Having the working directory set to system32 can cause several issues:

• Relative path references fail
• Configuration files can't be found
• DLL loading issues may occur

Here are three reliable approaches to change the working directory:

1. Modify During Service Startup (C# Example)

The most common approach is to change the directory when your service starts:

protected override void OnStart(string[] args)
{
    // Set working directory to service executable location
    string assemblyPath = System.Reflection.Assembly.GetExecutingAssembly().Location;
    string assemblyDir = Path.GetDirectoryName(assemblyPath);
    Directory.SetCurrentDirectory(assemblyDir);
    
    // Your service logic here
}

2. Using a Service Wrapper

Create a small executable that changes directory before launching your actual service:

static void Main(string[] args)
{
    string targetDir = @"C:\YourServiceDirectory";
    Directory.SetCurrentDirectory(targetDir);
    
    // Start the actual service
    Process.Start("YourActualService.exe");
}

3. Registry-Based Approach (Not Recommended)

While there is no direct registry key to set the working directory, you can use ImagePath with a wrapper:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\YourService]
"ImagePath"="\"C:\\Path\\To\\Wrapper.exe\" \"C:\\Path\\To\\YourService.exe\""

• Always use absolute paths for critical file operations
• Consider security implications of directory changes
• Test thoroughly as some APIs may cache the initial working directory
• Document this behavior in your deployment guides

For services implemented as DLLs (using svchost), you can specify ServiceDll with a relative path:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\YourService\Parameters]
"ServiceDll"=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,\
  74,00,25,00,5c,00,4d,00,79,00,53,00,65,00,72,00,76,00,69,00,63,00,65,00,2e,\
  00,64,00,6c,00,6c,00,00,00

When a Windows Service starts, it typically defaults to the system32 directory (usually C:\WINDOWS\system32). This can cause issues when your service needs to access files relative to its installation path or another specific directory.

While there isn't a direct registry key to set the working directory, you can create an ImagePath value that includes the working directory change as part of the executable path:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\YourServiceName]
"ImagePath"="cmd.exe /C \"cd /D C:\\Your\\Path && C:\\Path\\To\\YourService.exe\""

Note: This approach has limitations and may not work in all scenarios, especially with services that have specific security requirements.

The more reliable approach is to programmatically set the working directory when your service starts. Here are implementations in different languages:

C#/.NET Implementation

using System;
using System.IO;
using System.ServiceProcess;

public class YourService : ServiceBase
{
    protected override void OnStart(string[] args)
    {
        // Set working directory
        Directory.SetCurrentDirectory(AppDomain.CurrentDomain.BaseDirectory);
        
        // Your service startup code here
    }
}

C++ Implementation

#include <windows.h>
#include <tchar.h>

VOID WINAPI ServiceMain(DWORD argc, LPTSTR *argv)
{
    // Get service executable path
    TCHAR szPath[MAX_PATH];
    GetModuleFileName(NULL, szPath, MAX_PATH);
    
    // Extract directory
    TCHAR* p = _tcsrchr(szPath, '\\');
    if(p) *p = 0;
    
    // Set working directory
    SetCurrentDirectory(szPath);
    
    // Your service code here
}

• Always use absolute paths for critical file operations
• Consider storing configuration paths in the registry or configuration files
• Handle directory changes gracefully with proper error checking
• Document your service's working directory requirements

Another robust solution is to create a wrapper executable that sets the working directory before launching your actual service:

@echo off
cd /D "C:\Your\Service\Path"
start "YourService" "C:\Path\To\ActualService.exe"