diff --git a/json_serializable/lib/src/helper_core.dart b/json_serializable/lib/src/helper_core.dart
index 0a054f828..6877ee802 100644
--- a/json_serializable/lib/src/helper_core.dart
+++ b/json_serializable/lib/src/helper_core.dart
@@ -75,7 +75,11 @@ $converterOrKeyInstructions
 * Set `JsonSerializable.genericArgumentFactories` to `true`
   https://pub.dev/documentation/json_annotation/latest/json_annotation/JsonSerializable/genericArgumentFactories.html''';
   } else if (field.type != error.type) {
-    message = '$message because of type `${typeToCode(error.type)}`';
+    try {
+      message = '$message because of type `${typeToCode(error.type)}`';
+    } on UnimplementedError catch (ex) {
+      message = '$message because type is Unimplemented ($ex)';
+    }
   } else {
     final element = error.type.element?.name;
     todo = '''