From 58c3092ae361a3f611a1506ed24505357dbda12e Mon Sep 17 00:00:00 2001
From: Michael Staib <michael@chillicream.com>
Date: Wed, 25 Feb 2026 12:08:45 +0000
Subject: [PATCH] Fix payload error mapping for multiple constructors

---
 .../src/Types.Errors/ErrorFactoryCompiler.cs  |  2 +-
 .../ErrorMiddlewareTests.cs                   | 64 +++++++++++++++++++
 2 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/src/HotChocolate/Core/src/Types.Errors/ErrorFactoryCompiler.cs b/src/HotChocolate/Core/src/Types.Errors/ErrorFactoryCompiler.cs
index 70416ea7ee8..b3dde1f0404 100644
--- a/src/HotChocolate/Core/src/Types.Errors/ErrorFactoryCompiler.cs
+++ b/src/HotChocolate/Core/src/Types.Errors/ErrorFactoryCompiler.cs
@@ -174,7 +174,7 @@ private static bool TryCreateFactoryFromConstructor(
                         Expression.Assign(variable, createError),
                         previous is null
                             ? Expression.Assign(variable, nullValue)
-                            : Expression.Assign(variable, previous));
+                            : previous);
             }
         }
 
diff --git a/src/HotChocolate/Core/test/Types.Mutations.Tests/ErrorMiddlewareTests.cs b/src/HotChocolate/Core/test/Types.Mutations.Tests/ErrorMiddlewareTests.cs
index 0a394b03984..443cdfed764 100644
--- a/src/HotChocolate/Core/test/Types.Mutations.Tests/ErrorMiddlewareTests.cs
+++ b/src/HotChocolate/Core/test/Types.Mutations.Tests/ErrorMiddlewareTests.cs
@@ -1,3 +1,4 @@
+using System.Text.Json;
 using HotChocolate.Execution;
 using HotChocolate.Execution.Configuration;
 using Microsoft.Extensions.DependencyInjection;
@@ -195,6 +196,38 @@ await Snapshot.Create()
             .MatchAsync();
     }
 
+    [Fact]
+    public async Task ErrorMiddleware_Should_MapMultipleConstructors_FirstEx()
+    {
+        // Arrange
+        var executor =
+            await BuildSchemaAsync(
+                () => throw new InvalidOperationException(),
+                field => field.Error<CustomErrorWithMultipleConstructors>());
+
+        // Act
+        var res = await executor.ExecuteAsync(Query);
+
+        // Assert
+        AssertMappedPayloadError(res, "InvalidOperationException");
+    }
+
+    [Fact]
+    public async Task ErrorMiddleware_Should_MapMultipleConstructors_SecondEx()
+    {
+        // Arrange
+        var executor =
+            await BuildSchemaAsync(
+                () => throw new NullReferenceException(),
+                field => field.Error<CustomErrorWithMultipleConstructors>());
+
+        // Act
+        var res = await executor.ExecuteAsync(Query);
+
+        // Assert
+        AssertMappedPayloadError(res, "NullReferenceException");
+    }
+
     [Fact]
     public async Task ErrorMiddleware_Should_MapMultipleFactories_When_InterfaceIsUsed()
     {
@@ -366,6 +399,21 @@ public CustomNullRef CreateErrorFrom(NullReferenceException ex)
         }
     }
 
+    public class CustomErrorWithMultipleConstructors
+    {
+        public CustomErrorWithMultipleConstructors(InvalidOperationException _)
+        {
+            Message = "InvalidOperationException";
+        }
+
+        public CustomErrorWithMultipleConstructors(NullReferenceException _)
+        {
+            Message = "NullReferenceException";
+        }
+
+        public string Message { get; }
+    }
+
     public class CustomErrorPayloadErrorFactory
         : IPayloadErrorFactory<InvalidOperationException, CustomError>
         , IPayloadErrorFactory<NullReferenceException, CustomNullRef>
@@ -429,4 +477,20 @@ public class Payload
     {
         public string Foo() => "Bar";
     }
+
+    private static void AssertMappedPayloadError(IExecutionResult result, string expectedMessage)
+    {
+        using var document = JsonDocument.Parse(result.ToJson());
+
+        Assert.False(document.RootElement.TryGetProperty("errors", out _));
+
+        var message = document.RootElement
+            .GetProperty("data")
+            .GetProperty("throw")
+            .GetProperty("errors")[0]
+            .GetProperty("message")
+            .GetString();
+
+        Assert.Equal(expectedMessage, message);
+    }
 }