.NET 2.x X64 GetThreadContext Error 998: Invalid Access Memory Location - C#

if (!GetThreadContext(handle, ref context))
    throw new Win32Exception();

using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
 
namespace TestGetContext
{
    class Program
    {
        [DllImport("kernel32", SetLastError = true)]
        public static extern IntPtr OpenThread(int DesiredAccess, [MarshalAs(UnmanagedType.Bool)] bool bInheritHandle, int dwThreadId);
        [DllImport("kernel32", SetLastError = true)]
        public static extern uint SuspendThread(IntPtr thandle);
        [DllImport("kernel32", SetLastError = true)]
        public static extern uint ResumeThread(IntPtr thandle);
        [DllImport("kernel32", SetLastError = true)]
        public static extern bool GetThreadContext(IntPtr thandle, ref CONTEXT context);
 
        static void Main(string[] args)
        {
            Console.Write("Plese enter the thread Id: ");
            int id;
            if (!int.TryParse(Console.ReadLine(), out id))
                return;
 
            // open thread
            var handle = OpenThread(0x1FFFFF, false, id);
 
            try
            {
                if (handle == IntPtr.Zero)
                    throw new Win32Exception();
 
                if (SuspendThread(handle) == 0xFFFFFFFF)
                    throw new Win32Exception();
 
                var context = new CONTEXT { ContextFlags = 0x100001u /* CONTROL */ };
 
                if (!GetThreadContext(handle, ref context))
                    throw new Win32Exception();
 
                Console.WriteLine("Rip: 0x{0:X}", context.Rip);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally
            {
                ResumeThread(handle);
                Console.ReadLine();
            }
        }
    }
 
    [StructLayout(LayoutKind.Sequential/*, Size = 1232*/)]
    public struct CONTEXT
    {
        public ulong P1Home;
        public ulong P2Home;
        public ulong P3Home;
        public ulong P4Home;
        public ulong P5Home;
        public ulong P6Home;
        public uint ContextFlags;
        public uint MxCsr;
        public ushort SegCs;
        public ushort SegDs;
        public ushort SegEs;
        public ushort SegFs;
        public ushort SegGs;
        public ushort SegSs;
        public uint EFlags;
        public ulong Dr0;
        public ulong Dr1;
        public ulong Dr2;
        public ulong Dr3;
        public ulong Dr6;
        public ulong Dr7;
        public ulong Rax;
        public ulong Rcx;
        public ulong Rdx;
        public ulong Rbx;
        public ulong Rsp;
        public ulong Rbp;
        public ulong Rsi;
        public ulong Rdi;
        public ulong R8;
        public ulong R9;
        public ulong R10;
        public ulong R11;
        public ulong R12;
        public ulong R13;
        public ulong R14;
        public ulong R15;
        public ulong Rip;
 
        [MarshalAs(UnmanagedType.ByValArray, SizeConst=976)]
        private byte[] buff;
    };
}

#include <stdio.h>
#include <tchar.h>
#include <Windows.h>
 
int _tmain(int argc, _TCHAR* argv[])
{
    DWORD threadId = -1;
    printf("Please enter thread ID: ");
    scanf("%i", &threadId);
 
    if (threadId > 0)
    {
        HANDLE handle = OpenThread(THREAD_ALL_ACCESS, FALSE, threadId);
       
        SuspendThread(handle);
 
        CONTEXT context;
        context.ContextFlags = CONTEXT_CONTROL;
 
        GetThreadContext(handle, &context);
 
        printf("\nRip: 0x%X\n", context.Rip);
        ResumeThread(handle);
 
        CloseHandle(handle);
    }
 
    system("pause");
    return 0;
}