Issue 83667

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/DefaultJsonTypeInfoResolver.Converters.cs

@@ -156,7 +156,7 @@ internal static JsonConverter GetConverterForType(Type typeToConvert, JsonSerial
             converter = options.ExpandConverterFactory(converter, typeToConvert);
             if (!converter.TypeToConvert.IsInSubtypeRelationshipWith(typeToConvert))
             {
-                ThrowHelper.ThrowInvalidOperationException_SerializationConverterNotCompatible(converter.GetType(), converter.TypeToConvert);
+                ThrowHelper.ThrowInvalidOperationException_SerializationConverterNotCompatible(converter.GetType(), typeToConvert);
             }
 
             JsonSerializerOptions.CheckConverterNullabilityIsSameAsPropertyType(converter, typeToConvert);

src/libraries/System.Text.Json/tests/System.Text.Json.Tests/Serialization/CustomConverterTests/CustomConverterTests.cs

@@ -221,5 +221,25 @@ public static void GetConverterTypeToConvertNull()
         {
             Assert.Throws<ArgumentNullException>(() => (new JsonSerializerOptions()).GetConverter(typeToConvert: null!));
         }
+
+        [Fact]
+        public static void ErrorMessageContainsExpectedType()
+        {
+            JsonSerializerOptions options = new();
+            options.Converters.Add(new InvalidJsonConverterFactory());
+            var ex = Assert.Throws<InvalidOperationException>(() => 
+                JsonSerializer.Serialize(new InvalidTestInfo("Hello"), options));
+            Assert.Contains(typeof(InvalidTestInfo).Name, ex.Message);
+        }
+
+        private sealed record InvalidTestInfo(string Name);
+
+        private sealed class InvalidJsonConverterFactory : JsonConverterFactory
+        {
+            public override bool CanConvert(Type typeToConvert) => true;
+
+            public override JsonConverter? CreateConverter(Type typeToConvert, JsonSerializerOptions options)
+                => new MyBoolEnumConverter();
+        }
     }
 }