How do I force my .NET application to run as administrator?

You'll want to modify the manifest that gets embedded in the program. This works on Visual Studio 2008 and higher: Project + Add New Item, select "Application Manifest File". Change the <requestedExecutionLevel> element to:

 <requestedExecutionLevel level="requireAdministrator" uiAccess="false" />

The user gets the UAC prompt when they start the program. Use wisely; their patience can wear out quickly.

Adding a requestedExecutionLevel element to your manifest is only half the battle; you have to remember that UAC can be turned off. If it is, you have to perform the check the old school way and put up an error dialog if the user is not administrator
(call IsInRole(WindowsBuiltInRole.Administrator) on your thread's CurrentPrincipal).

The detailed steps are as follow.

Add application manifest file to project Change application setting to "app.manifest" Update tag of "requestedExecutionLevel" to requireAdministrator.

https://i.stack.imgur.com/5DeDz.png

https://i.stack.imgur.com/tmaVc.png

https://i.stack.imgur.com/bkdgo.png

https://i.stack.imgur.com/nyJPq.png

Note that using this code you need to turn off the security settings of ClickOnce, for do this, go inside Properties -> Security -> ClickOnce Security

I implemented some code to do it manually:

using System.Security.Principal;
public bool IsUserAdministrator()
{
    bool isAdmin;
    try
    {
        WindowsIdentity user = WindowsIdentity.GetCurrent();
        WindowsPrincipal principal = new WindowsPrincipal(user);
        isAdmin = principal.IsInRole(WindowsBuiltInRole.Administrator);
    }
    catch (UnauthorizedAccessException ex)
    {
        isAdmin = false;
    }
    catch (Exception ex)
    {
        isAdmin = false;
    }
    return isAdmin;
}

You can embed a manifest file in the EXE file, which will cause Windows (7 or higher) to always run the program as an administrator.

You can find more details in Step 6: Create and Embed an Application Manifest (UAC) (MSDN).

While working on Visual Studio 2008, right click on Project -> Add New Item and then chose Application Manifest File.

In the manifest file, you will find the tag requestedExecutionLevel, and you may set the level to three values:

<requestedExecutionLevel level="asInvoker" uiAccess="false" />

OR

<requestedExecutionLevel level="requireAdministrator" uiAccess="false" />

OR

<requestedExecutionLevel level="highestAvailable" uiAccess="false" />

To set your application to run as administrator, you have to chose the middle one.

Another way of doing this, in code only, is to detect if the process is running as admin like in the answer by @NG.. And then open the application again and close the current one.

I use this code when an application only needs admin privileges when run under certain conditions, such as when installing itself as a service. So it doesn't need to run as admin all the time like the other answers force it too.

Note in the below code NeedsToRunAsAdmin is a method that detects if under current conditions admin privileges are required. If this returns false the code will not elevate itself. This is a major advantage of this approach over the others.

Although this code has the advantages stated above, it does need to re-launch itself as a new process which isn't always what you want.

private static void Main(string[] args)
{
    if (NeedsToRunAsAdmin() && !IsRunAsAdmin())
    {
        ProcessStartInfo proc = new ProcessStartInfo();
        proc.UseShellExecute = true;
        proc.WorkingDirectory = Environment.CurrentDirectory;
        proc.FileName = Assembly.GetEntryAssembly().CodeBase;

        foreach (string arg in args)
        {
            proc.Arguments += String.Format("\"{0}\" ", arg);
        }

        proc.Verb = "runas";

        try
        {
            Process.Start(proc);
        }
        catch
        {
            Console.WriteLine("This application requires elevated credentials in order to operate correctly!");
        }
    }
    else
    {
        //Normal program logic...
    }
}

private static bool IsRunAsAdmin()
{
    WindowsIdentity id = WindowsIdentity.GetCurrent();
    WindowsPrincipal principal = new WindowsPrincipal(id);

    return principal.IsInRole(WindowsBuiltInRole.Administrator);
}

As per

<requestedExecutionLevel level="highestAvailable" uiAccess="false" />

you will want to add an application manifest if you don't already have one or don't know how to add one. As some projects don't automatically add a separate manifest file, first go to project properties, navigate to the Application tab and check to make sure your project is not excluding the manifest at the bottom of the tap.

Next, right click project

Add new Item

Last, find and click Application Manifest File

In Visual Studio 2010 right click your project name. Hit "View Windows Settings", this generates and opens a file called "app.manifest". Within this file replace "asInvoker" with "requireAdministrator" as explained in the commented sections within the file.

You can create the manifest using ClickOnce Security Settings, and then disable it:

Right click on the Project -> Properties -> Security -> Enable ClickOnce Security Settings

After you clicked it, a file will be created under the Project's properties folder called app.manifest once this is created, you can uncheck the Enable ClickOnce Security Settings option

Open that file and change this line :

<requestedExecutionLevel level="asInvoker" uiAccess="false" />

to:

 <requestedExecutionLevel  level="requireAdministrator" uiAccess="false" />

This will make the program require administrator privileges.

THIS DOES NOT FORCE APPLICATION TO WORK AS ADMINISTRATOR.
This is a simplified version of the this answer, above by @NG

public bool IsUserAdministrator()
{
    try
    {
        WindowsIdentity user = WindowsIdentity.GetCurrent();
        WindowsPrincipal principal = new WindowsPrincipal(user);
        return principal.IsInRole(WindowsBuiltInRole.Administrator);
    }
    catch
    {
        return false;
    }
}

In case you want a code-only solution for some reason, here's a standalone class file. Just call "AdminRelauncher.RelaunchIfNotAdmin()" at application start:

using System;
using System.Diagnostics;
using System.Reflection;
using System.Security.Principal;

public static class AdminRelauncher
{
    public static void RelaunchIfNotAdmin()
    {
        if (!RunningAsAdmin())
        {
            Console.WriteLine("Running as admin required!");
            ProcessStartInfo proc = new ProcessStartInfo();
            proc.UseShellExecute = true;
            proc.WorkingDirectory = Environment.CurrentDirectory;
            proc.FileName = Assembly.GetEntryAssembly().CodeBase;
            proc.Verb = "runas";
            try
            {
                Process.Start(proc);
                Environment.Exit(0);
            }
            catch (Exception ex)
            {
                Console.WriteLine("This program must be run as an administrator! \n\n" + ex.ToString());
                Environment.Exit(0);
            }
        }
    }

    private static bool RunningAsAdmin() 
    {
        WindowsIdentity id = WindowsIdentity.GetCurrent();
        WindowsPrincipal principal = new WindowsPrincipal(id);

        return principal.IsInRole(WindowsBuiltInRole.Administrator);
    }
}

Right click your executable, go to Properties > Compatibility and check the 'Run this program as admin' box.

If you want to run it as admin for all users, do the same thing in 'change setting for all users'.