Capturing and rethrowing with original stack trace

Context: Using ExceptionDispatchInfo, you can capture an exception and later rethrow it without losing the original stack trace. This is different from throw ex; (which resets the stack) and throw; (which only works inside the original catch block). It is especially valuable when exceptions cross thread or async boundaries.

Usage Example

using System;
using System.Runtime.ExceptionServices;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        ExceptionDispatchInfo info = null;

        try
        {
            await Task.Run(() => throw new ArgumentException("Bad argument"));
        }
        catch (ArgumentException ex)
        {
            info = ExceptionDispatchInfo.Capture(ex);
        }

        // Later (possibly in another method)
        try
        {
            info?.Throw();
        }
        catch (ArgumentException ex)
        {
            Console.WriteLine($"Rethrown: {ex.Message}");
            Console.WriteLine(ex.StackTrace);
        }
    }
}

Output console

dotnet run
Rethrown: Bad argument
   at Program.<>c.<Main>b__0_0() in ...
   at System.Threading.Tasks.Task`1.InnerInvoke()
   ...

Important notes

• The captured exception’s original stack trace is preserved.
• You can store the ExceptionDispatchInfo in a field or collection.
• Avoid capturing the same exception multiple times (it works, but unnecessary).

Real-world usage example

AggregateException handling – When flattening AggregateException in parallel loops, capture each inner exception and rethrow later.
See .NET docs on rethrowing exceptions.

Related sections

• 12.4 ExceptionDispatchInfo
• 12.5.3 TaskScheduler UnobservedTaskException