react · JoaoPauloCMarra · Aug 6, 2026
diff --git a/packages/react-native/React/DevSupport/RCTPackagerConnection.mm b/packages/react-native/React/DevSupport/RCTPackagerConnection.mm
@@ -262,14 +262,30 @@ - (void)reconnectingWebSocketDidOpen:(__unused RCTReconnectingWebSocket *)webSoc
 
 - (void)reconnectingWebSocket:(RCTReconnectingWebSocket *)webSocket didReceiveMessage:(id)message
 {
+  if (![message isKindOfClass:[NSString class]]) {
+    RCTLogError(@"%@ received a packager message with an unsupported type %@", [self class], [message class]);
+    return;
+  }
+
   NSError *error = nil;
-  NSDictionary<NSString *, id> *msg = RCTJSONParse(message, &error);
+  id parsedMessage = RCTJSONParse((NSString *)message, &error);
 
   if (error) {
-    RCTLogError(@"%@ failed to parse message with error %@\n<message>\n%@\n</message>", [self class], error, msg);
+    RCTLogError(
+        @"%@ failed to parse message with error %@\n<message>\n%@\n</message>", [self class], error, message);
     return;
   }
 
+  if (![parsedMessage isKindOfClass:[NSDictionary class]]) {
+    RCTLogError(
+        @"%@ received a packager message that was not a JSON object\n<message>\n%@\n</message>",
+        [self class],
+        message);
+    return;
+  }
+
+  NSDictionary<NSString *, id> *msg = parsedMessage;
+
   if (!isSupportedVersion(msg[@"version"])) {
     RCTLogError(@"%@ received message with not supported version %@", [self class], msg[@"version"]);
     return;

diff --git a/packages/rn-tester/RNTesterPods.xcodeproj/project.pbxproj b/packages/rn-tester/RNTesterPods.xcodeproj/project.pbxproj
@@ -18,6 +18,7 @@
 		8145AE06241172D900A3F8DA /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 8145AE05241172D900A3F8DA /* LaunchScreen.storyboard */; };
 		832F45BB2A8A6E1F0097B4E6 /* SwiftTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = 832F45BA2A8A6E1F0097B4E6 /* SwiftTest.swift */; };
 		A975CA6C2C05EADF0043F72A /* RCTNetworkTaskTests.m in Sources */ = {isa = PBXBuildFile; fileRef = A975CA6B2C05EADE0043F72A /* RCTNetworkTaskTests.m */; };
+		B4810BCE2F3D4A5B6C7D8E9F /* RCTPackagerConnectionTests.m in Sources */ = {isa = PBXBuildFile; fileRef = B4810BCD2F3D4A5B6C7D8E9F /* RCTPackagerConnectionTests.m */; };
 		C175B6D9ED9336FB66637943 /* libPods-RNTester.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 4C706D402EE4AF9BE838CBA9 /* libPods-RNTester.a */; };
 		CD10C7A5290BD4EB0033E1ED /* RCTEventEmitterTests.m in Sources */ = {isa = PBXBuildFile; fileRef = CD10C7A4290BD4EB0033E1ED /* RCTEventEmitterTests.m */; };
 		E62F11832A5C6580000BF1C8 /* FlexibleSizeExampleView.mm in Sources */ = {isa = PBXBuildFile; fileRef = 27F441E81BEBE5030039B79C /* FlexibleSizeExampleView.mm */; };
@@ -96,6 +97,7 @@
 		832F45BA2A8A6E1F0097B4E6 /* SwiftTest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = SwiftTest.swift; path = RNTester/SwiftTest.swift; sourceTree = "<group>"; };
 		93A243F0D4D5C54911E811C4 /* libPods-RNTesterIntegrationTests.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = "libPods-RNTesterIntegrationTests.a"; sourceTree = BUILT_PRODUCTS_DIR; };
 		A975CA6B2C05EADE0043F72A /* RCTNetworkTaskTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = RCTNetworkTaskTests.m; sourceTree = "<group>"; };
+		B4810BCD2F3D4A5B6C7D8E9F /* RCTPackagerConnectionTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = RCTPackagerConnectionTests.m; sourceTree = "<group>"; };
 		AC474BFB29BBD4A1002BDAED /* RNTester.xctestplan */ = {isa = PBXFileReference; lastKnownFileType = text; name = RNTester.xctestplan; path = RNTester/RNTester.xctestplan; sourceTree = "<group>"; };
 		B0E70A8A05E03E868F8703FE /* Pods-RNTesterIntegrationTests.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-RNTesterIntegrationTests.release.xcconfig"; path = "Target Support Files/Pods-RNTesterIntegrationTests/Pods-RNTesterIntegrationTests.release.xcconfig"; sourceTree = "<group>"; };
 		CA59C9994B1822826D8983F0 /* Pods-RNTester.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-RNTester.debug.xcconfig"; path = "Target Support Files/Pods-RNTester/Pods-RNTester.debug.xcconfig"; sourceTree = "<group>"; };
@@ -337,6 +339,7 @@
 				F1A0B1C23D4E5F6071829301 /* RCTTurboModuleArrayBufferTests.mm */,
 				E7DB20CF22B2BAA5005AC45F /* RCTMultipartStreamReaderTests.m */,
 				A975CA6B2C05EADE0043F72A /* RCTNetworkTaskTests.m */,
+				B4810BCD2F3D4A5B6C7D8E9F /* RCTPackagerConnectionTests.m */,
 				E7DB20BE22B2BAA4005AC45F /* RCTNativeAnimatedNodesManagerTests.m */,
 				E7DB20AD22B2BAA3005AC45F /* RCTPerformanceLoggerTests.m */,
 				E7DB20C122B2BAA4005AC45F /* RCTUnicodeDecodeTests.m */,
@@ -741,6 +744,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				A975CA6C2C05EADF0043F72A /* RCTNetworkTaskTests.m in Sources */,
+				B4810BCE2F3D4A5B6C7D8E9F /* RCTPackagerConnectionTests.m in Sources */,
 				E7DB20DF22B2BAA6005AC45F /* RCTImageLoaderTests.m in Sources */,
 				E7DB20D222B2BAA6005AC45F /* RCTModuleInitNotificationRaceTests.m in Sources */,
 				E7DB20D522B2BAA6005AC45F /* RCTPerformanceLoggerTests.m in Sources */,

diff --git a/packages/rn-tester/RNTesterUnitTests/RCTPackagerConnectionTests.m b/packages/rn-tester/RNTesterUnitTests/RCTPackagerConnectionTests.m
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import <XCTest/XCTest.h>
+
+#import <React/RCTPackagerClient.h>
+#import <React/RCTPackagerConnection.h>
+#import <React/RCTReconnectingWebSocket.h>
+
+@interface RCTPackagerConnection (Testing)
+
+- (void)reconnectingWebSocket:(RCTReconnectingWebSocket *)webSocket didReceiveMessage:(id)message;
+
+@end
+
+@interface RCTPackagerConnectionTests : XCTestCase
+
+@end
+
+@implementation RCTPackagerConnectionTests
+
+- (void)testIgnoresBinaryMessages
+{
+  RCTPackagerConnection *connection = [RCTPackagerConnection new];
+  NSData *message = [@"{}" dataUsingEncoding:NSUTF8StringEncoding];
+
+  XCTAssertNoThrow([connection reconnectingWebSocket:nil didReceiveMessage:message]);
+}
+
+- (void)testIgnoresNonObjectMessages
+{
+  RCTPackagerConnection *connection = [RCTPackagerConnection new];
+
+  XCTAssertNoThrow([connection reconnectingWebSocket:nil didReceiveMessage:@"[]"]);
+}
+
+- (void)testDispatchesValidNotification
+{
+  XCTestExpectation *expectation = [self expectationWithDescription:@"Notification handler is called"];
+  __block NSDictionary<NSString *, id> *receivedParams;
+  RCTPackagerConnection *connection = [RCTPackagerConnection new];
+  dispatch_queue_t queue = dispatch_queue_create("RCTPackagerConnectionTests", DISPATCH_QUEUE_SERIAL);
+
+  [connection addNotificationHandler:^(NSDictionary<NSString *, id> *params) {
+    receivedParams = params;
+    [expectation fulfill];
+  }
+                                      queue:queue
+                                  forMethod:@"reload"];
+
+  NSString *message = [NSString stringWithFormat:
+                                 @"{\"version\":%d,\"method\":\"reload\",\"params\":{\"value\":1}}",
+                                 RCT_PACKAGER_CLIENT_PROTOCOL_VERSION];
+  [connection reconnectingWebSocket:nil didReceiveMessage:message];
+
+  [self waitForExpectations:@[ expectation ] timeout:1.0];
+  XCTAssertEqualObjects(receivedParams, (@{ @"value" : @1 }));
+}
+
+@end