diff --git a/swagger_parser/CHANGELOG.md b/swagger_parser/CHANGELOG.md
index ae6a390c..3c5a6779 100644
--- a/swagger_parser/CHANGELOG.md
+++ b/swagger_parser/CHANGELOG.md
@@ -1,3 +1,6 @@
+## 1.20.1
+- Fixed errors with config parsing
+
 ## 1.20.0
 - Add validation params to generated `freezed` classes
 - Fixed errors with empty schema properties([#280](https://github.com/Carapacik/swagger_parser/issues/280))
diff --git a/swagger_parser/lib/src/config/swp_config.dart b/swagger_parser/lib/src/config/swp_config.dart
index ca4c4633..fe66c59b 100644
--- a/swagger_parser/lib/src/config/swp_config.dart
+++ b/swagger_parser/lib/src/config/swp_config.dart
@@ -150,10 +150,10 @@ class SWPConfig {
       );
     }
 
-    final mergeClients = yamlMap['mergeClients'];
+    final mergeClients = yamlMap['merge_clients'];
     if (mergeClients is! bool?) {
       throw const ConfigException(
-        "Config parameter 'mergeClients' must be bool.",
+        "Config parameter 'merge_clients' must be bool.",
       );
     }
 
@@ -193,6 +193,8 @@ class SWPConfig {
     final rawJsonSerializer = yamlMap['json_serializer']?.toString();
     if (rawJsonSerializer != null) {
       jsonSerializer = JsonSerializer.fromString(rawJsonSerializer);
+    } else if (rootConfig?.jsonSerializer != null) {
+      jsonSerializer = rootConfig!.jsonSerializer;
     }
 
     final rootClient = yamlMap['root_client'];
diff --git a/swagger_parser/lib/src/generator/model/programming_language.dart b/swagger_parser/lib/src/generator/model/programming_language.dart
index f4ca4bc0..b7ef9b76 100644
--- a/swagger_parser/lib/src/generator/model/programming_language.dart
+++ b/swagger_parser/lib/src/generator/model/programming_language.dart
@@ -63,25 +63,21 @@ enum ProgrammingLanguage {
               markFileAsGenerated: markFilesAsGenerated,
             );
           }
-
-          switch (jsonSerializer) {
-            case JsonSerializer.freezed:
-              return dartFreezedDtoTemplate(
+          return switch (jsonSerializer) {
+            JsonSerializer.freezed => dartFreezedDtoTemplate(
                 dataClass,
                 markFileAsGenerated: markFilesAsGenerated,
                 generateValidator: generateValidator,
-              );
-            case JsonSerializer.jsonSerializable:
-              return dartJsonSerializableDtoTemplate(
+              ),
+            JsonSerializer.jsonSerializable => dartJsonSerializableDtoTemplate(
                 dataClass,
                 markFileAsGenerated: markFilesAsGenerated,
-              );
-            case JsonSerializer.dartMappable:
-              return dartDartMappableDtoTemplate(
+              ),
+            JsonSerializer.dartMappable => dartDartMappableDtoTemplate(
                 dataClass,
                 markFileAsGenerated: markFilesAsGenerated,
-              );
-          }
+              )
+          };
         }
       case kotlin:
         if (dataClass is UniversalEnumClass) {
diff --git a/swagger_parser/pubspec.yaml b/swagger_parser/pubspec.yaml
index e3aca081..fb690451 100644
--- a/swagger_parser/pubspec.yaml
+++ b/swagger_parser/pubspec.yaml
@@ -1,6 +1,6 @@
 name: swagger_parser
 description: Package that generates REST clients and data classes from OpenApi definition file
-version: 1.20.0
+version: 1.20.1
 repository: https://github.com/Carapacik/swagger_parser/tree/main/swagger_parser
 topics:
   - swagger