Access Violation Exception EnterCriticalSection WinAPI C#

I don't understand what is causing this error

[DllImport("kernel32.dll")]
static extern void EnterCriticalSection(ref IntPtr lpCriticalSection);

[DllImport("kernel32.dll")]
static extern void LeaveCriticalSection(ref IntPtr lpCriticalSection);

public Form1()
{
   InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
    unsafe
    {
        try
        {
            IntPtr criticalSection = new IntPtr();
            EnterCriticalSection(ref criticalSection);
            LeaveCriticalSection(ref criticalSection);
        }
        catch (AccessViolationException exception)
        {
            Console.WriteLine(exception.Message);
        }
    }
}

I tried in Visual Studio to change the build type from Any CPU to x86, but it didn't bring results.

EnterCriticalSection() expects to be given a pointer to a CRITICAL_SECTION struct that has been initialized with either InitializeCriticalSection() or InitializeCriticalSectionAndSpinCount().

But instead, you are giving it a reference to an uninitialized IntPtr that doesn't point anywhere meaningful. Hence the crash when EnterCriticalSection() tries to access a struct that doesn't exist.

The correct code should look more like this:

[StructLayout(LayoutKind.Sequential)]
public struct CRITICAL_SECTION
{
    public IntPtr DebugInfo;
    public int LockCount;
    public int RecursionCount;
    public IntPtr OwningThread;
    public IntPtr LockSemaphore;
    public UIntPtr SpinCount;
}

[DllImport("kernel32.dll")]
static extern void InitializeCriticalSection(ref CRITICAL_SECTION lpCriticalSection);

[DllImport("kernel32.dll")]
static extern void DeleteCriticalSection(ref CRITICAL_SECTION lpCriticalSection);

[DllImport("kernel32.dll")]
static extern void EnterCriticalSection(ref CRITICAL_SECTION lpCriticalSection);

[DllImport("kernel32.dll")]
static extern void LeaveCriticalSection(ref CRITICAL_SECTION lpCriticalSection);

public Form1()
{
   InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
    unsafe
    {
        try
        {
            CRITICAL_SECTION criticalSection = new CRITICAL_SECTION();
            InitializeCriticalSection(ref criticalSection);
            EnterCriticalSection(ref criticalSection);
            LeaveCriticalSection(ref criticalSection);
            DeleteCriticalSection(ref criticalSection);
        }
        catch (AccessViolationException exception)
        {
            Console.WriteLine(exception.Message);
        }
    }
}

However, you really don't need to use CRITICAL_SECTION in C#, use the lock statement instead, or a synchronization primitive like System.Threading.Monitor.