From 5e5e6be259a0285f38e4403477fe9c7d3dbfa73e Mon Sep 17 00:00:00 2001
From: Chris Midgley <chris.midgley@dunecomputers.co.uk>
Date: Mon, 25 Aug 2025 11:08:26 +0100
Subject: [PATCH] Add OriginalMessage property to CsvHelperException.

This records the original message, without any extra details about row
indexes etc.

Fixes #2157.
---
 src/CsvHelper/CsvHelperException.cs           | 22 ++++++++++++--
 .../CsvHelperExceptionTests.cs                | 29 +++++++++++++++++++
 2 files changed, 48 insertions(+), 3 deletions(-)
 create mode 100644 tests/CsvHelper.Tests/CsvHelperExceptionTests.cs

diff --git a/src/CsvHelper/CsvHelperException.cs b/src/CsvHelper/CsvHelperException.cs
index fe8b90f3f..b4f0f514a 100644
--- a/src/CsvHelper/CsvHelperException.cs
+++ b/src/CsvHelper/CsvHelperException.cs
@@ -16,11 +16,19 @@ public class CsvHelperException : Exception
 	[NonSerialized]
 	private readonly CsvContext? context;
 
+	[NonSerialized]
+	private readonly string originalMessage = "";
+
 	/// <summary>
 	/// Gets the context.
 	/// </summary>
 	public CsvContext? Context => context;
 
+	/// <summary>
+	/// Gets the original error message, without added details.
+	/// </summary>
+	public string OriginalMessage => originalMessage;
+
 	/// <summary>
 	/// Initializes a new instance of the CsvHelperException class.
 	/// </summary>
@@ -30,14 +38,20 @@ internal protected CsvHelperException() : base() { }
 	/// Initializes a new instance of the CsvHelperException class.
 	/// </summary>
 	/// <param name="message">The message that describes the error.</param>
-	internal protected CsvHelperException(string message) : base(message) { }
+	internal protected CsvHelperException(string message) : base(message)
+	{
+		originalMessage = message;
+	}
 
 	/// <summary>
 	/// Initializes a new instance of the CsvHelperException class.
 	/// </summary>
 	/// <param name="message">The error message that explains the reason for the exception.</param>
 	/// <param name="innerException">The exception that is the cause of the current exception, or a null reference (Nothing in Visual Basic) if no inner exception is specified.</param>
-	internal protected CsvHelperException(string message, Exception innerException) : base(message, innerException) { }
+	internal protected CsvHelperException(string message, Exception innerException) : base(message, innerException)
+	{
+		originalMessage = message;
+	}
 
 	/// <summary>
 	/// Initializes a new instance of the <see cref="CsvHelperException"/> class.
@@ -56,11 +70,12 @@ public CsvHelperException(CsvContext context)
 	public CsvHelperException(CsvContext context, string message) : base(AddDetails(message, context))
 	{
 		this.context = context;
+		originalMessage = message;
 	}
 
 	/// <summary>
 	/// Initializes a new instance of the <see cref="CsvHelperException"/> class
-	/// with a specified error message and a reference to the inner exception that 
+	/// with a specified error message and a reference to the inner exception that
 	/// is the cause of this exception.
 	/// </summary>
 	/// <param name="context">The context.</param>
@@ -69,6 +84,7 @@ public CsvHelperException(CsvContext context, string message) : base(AddDetails(
 	public CsvHelperException(CsvContext context, string message, Exception innerException) : base(AddDetails(message, context), innerException)
 	{
 		this.context = context;
+		originalMessage = message;
 	}
 
 	private static string AddDetails(string message, CsvContext context)
diff --git a/tests/CsvHelper.Tests/CsvHelperExceptionTests.cs b/tests/CsvHelper.Tests/CsvHelperExceptionTests.cs
new file mode 100644
index 000000000..9fc1cf4cb
--- /dev/null
+++ b/tests/CsvHelper.Tests/CsvHelperExceptionTests.cs
@@ -0,0 +1,29 @@
+using System.Globalization;
+using CsvHelper.Configuration;
+using CsvHelper.Tests.Mocks;
+using Xunit;
+
+namespace CsvHelper.Tests;
+
+public class CsvHelperExceptionTests
+{
+	[Fact]
+	public void ExceptionStoresOriginalMessageInOriginalMessage()
+	{
+		var config = new CsvConfiguration(CultureInfo.InvariantCulture)
+		{
+			HasHeaderRecord = false,
+		};
+		var parser = new ParserMock(config)
+		{
+			{ "Id", "Name" }
+		};
+
+		var csv = new CsvReader(parser);
+
+		var error = Assert.Throws<ReaderException>(() => csv.ReadHeader());
+		Assert.StartsWith("Configuration.HasHeaderRecord is false.", error.Message);
+		Assert.NotEqual("Configuration.HasHeaderRecord is false.", error.Message);
+		Assert.Equal("Configuration.HasHeaderRecord is false.", error.OriginalMessage);
+	}
+}