diff --git a/packages/ferry/lib/src/request_controller_typed_link.dart b/packages/ferry/lib/src/request_controller_typed_link.dart
index a989a1f1..83457ad9 100644
--- a/packages/ferry/lib/src/request_controller_typed_link.dart
+++ b/packages/ferry/lib/src/request_controller_typed_link.dart
@@ -69,7 +69,7 @@ class RequestControllerTypedLink extends TypedLink {
           /// Temporarily add a listener so that [prev] doesn't shut down when
           /// switchMap is updating the stream.
           final sub = prev?.listen(null);
-          scheduleMicrotask(() => sub?.cancel());
+          Future.delayed(Duration.zero, () => sub?.cancel());
         },
       ).switchMap(
         (req) {
diff --git a/packages/ferry/pubspec.yaml b/packages/ferry/pubspec.yaml
index e41b7871..7bbf8e42 100644
--- a/packages/ferry/pubspec.yaml
+++ b/packages/ferry/pubspec.yaml
@@ -12,7 +12,7 @@ topics:
   - ferry
 dependencies:
   gql: '>=0.14.0 <2.0.0'
-  rxdart: ^0.27.1
+  rxdart: ^0.28.0
   gql_link: '>=0.5.0 <2.0.0'
   gql_exec: '>=0.4.0 <2.0.0'
   meta: ^1.3.0
diff --git a/packages/ferry/test/client/json_operation_test.dart b/packages/ferry/test/client/json_operation_test.dart
index 0e73a580..90017808 100644
--- a/packages/ferry/test/client/json_operation_test.dart
+++ b/packages/ferry/test/client/json_operation_test.dart
@@ -15,18 +15,21 @@ void main() {
 
     addTearDown(client.dispose);
 
-    final req =
-        JsonOperationRequest(operation: Operation(document: gql.parseString(r'''
+    final req = JsonOperationRequest(
+      operation: Operation(document: gql.parseString(r'''
        query Reviews {
             reviews(episode: $episode, first: $first, offset: $offset) {
               id
               stars
             }
-          }''')), fetchPolicy: FetchPolicy.CacheFirst, vars: {
-      'episode': 'NEWHOPE',
-      'first': 3,
-      'offset': 0,
-    });
+          }''')),
+      fetchPolicy: FetchPolicy.CacheFirst,
+      vars: {
+        'episode': 'NEWHOPE',
+        'first': 3,
+        'offset': 0,
+      },
+    );
 
     final result = await client.request(req).first;
 
diff --git a/packages/ferry_cache/lib/src/utils/operation_root_data.dart b/packages/ferry_cache/lib/src/utils/operation_root_data.dart
index 561f67eb..33ecdd90 100644
--- a/packages/ferry_cache/lib/src/utils/operation_root_data.dart
+++ b/packages/ferry_cache/lib/src/utils/operation_root_data.dart
@@ -13,8 +13,8 @@ Map<String, dynamic> operationRootData<TData, TVars>(
 ) {
   final fieldNames = operationFieldNames(
     request.operation.document,
-    request.operation.operationName!,
-    (request.vars as dynamic).toJson(),
+    request.operation.operationName,
+    request.varsToJson(),
     typePolicies,
     possibleTypes,
   );
diff --git a/packages/ferry_cache/pubspec.yaml b/packages/ferry_cache/pubspec.yaml
index 985a62c2..42b64535 100644
--- a/packages/ferry_cache/pubspec.yaml
+++ b/packages/ferry_cache/pubspec.yaml
@@ -12,7 +12,7 @@ topics:
 dependencies:
   ferry_exec: ^0.6.1-dev.1
   meta: ^1.3.0
-  rxdart: ^0.27.1
+  rxdart: ^0.28.0
   normalize: ^0.9.1
   ferry_store: ^0.6.0-dev.0
   collection: ^1.15.0
diff --git a/packages/ferry_hive_store/pubspec.yaml b/packages/ferry_hive_store/pubspec.yaml
index e8eeee7e..83960b4e 100644
--- a/packages/ferry_hive_store/pubspec.yaml
+++ b/packages/ferry_hive_store/pubspec.yaml
@@ -13,7 +13,7 @@ topics:
 dependencies:
   hive: ^2.0.0
   ferry_store: ^0.6.0-dev.0
-  rxdart: ^0.27.1
+  rxdart: ^0.28.0
   collection: ^1.15.0
 dev_dependencies:
   test: ^1.16.8
diff --git a/packages/ferry_store/pubspec.yaml b/packages/ferry_store/pubspec.yaml
index 55cf3320..0ab09de2 100644
--- a/packages/ferry_store/pubspec.yaml
+++ b/packages/ferry_store/pubspec.yaml
@@ -10,7 +10,7 @@ topics:
   - gql
   - ferry
 dependencies:
-  rxdart: ^0.27.1
+  rxdart: ^0.28.0
   collection: ^1.15.0
 dev_dependencies:
   test: ^1.16.8
diff --git a/packages/normalize/lib/src/utils/operation_field_names.dart b/packages/normalize/lib/src/utils/operation_field_names.dart
index 5a22fe9c..eb426fff 100644
--- a/packages/normalize/lib/src/utils/operation_field_names.dart
+++ b/packages/normalize/lib/src/utils/operation_field_names.dart
@@ -10,7 +10,7 @@ import 'package:normalize/src/policies/type_policy.dart';
 /// Returns the root field names for a given operation.
 List<String> operationFieldNames<TData, TVars>(
   DocumentNode document,
-  String operationName,
+  String? operationName,
   Map<String, dynamic> vars,
   Map<String, TypePolicy> typePolicies,
   Map<String, Set<String>> possibleTypes,