I’m trying to run this project DbMon.NET – A simple .NET OutputDebugString capturer in .NET Core (.NET 5.0).

It runs fine in .Net Framework 4.7.2, but when I switch to .NET 5, I keep getting the exception System.OverflowException: Arithmetic operation resulted in an overflow. thrown by System.IntPtr.ToInt32().

Here is the details:

Step 1: Download DbMon.NET source code.

Step 2: Add the file DebugMonitor.cs to my .NET 5.0 console project.

Step 3: I execute DebugMonitor in the file Program.cs like this:

        static void Main(string[] args)
        {
            DebugMonitor.OnOutputDebugString += new OnOutputDebugStringHandler(PrintDebugString);
            DebugMonitor.Start();

            Console.Read();
            DebugMonitor.Stop();
        }

        private static void PrintDebugString(int id, string szMsg)
            => Console.WriteLine("{0} - {1}", id, szMsg);

Step 4: Run the project. The code always throw exception at m_SharedMem.ToInt32() in the file DebugMonitor.cs. the value of m_SharedMem is m_SharedMem = MapViewOfFile(m_SharedFile, SECTION_MAP_READ, 0, 0, 512);.

The exception is: System.OverflowException: Arithmetic operation resulted in an overflow..

In step 2, if I use .NET Framework 4.7.2 instead of .NET 5.0, I won’t get the exception. So I guess .NET 5.0 might require to setup some security rule or something, I have this this question (MemoryMappedFile low-integrity .Net 5) but haven’t figured out how to fix this DbMon.Net in .Net Core 5.0.