diff --git a/React/Base/RCTDefines.h b/React/Base/RCTDefines.h
index b3b017dff..a79f76b30 100644
--- a/React/Base/RCTDefines.h
+++ b/React/Base/RCTDefines.h
@@ -56,6 +56,14 @@
 #endif
 #endif
 
+#ifndef ENABLE_PACKAGER_CONNECTION
+#if RCT_DEV && __has_include(<React/RCTPackagerConnection.h>)
+#define ENABLE_PACKAGER_CONNECTION 1
+#else
+#define ENABLE_PACKAGER_CONNECTION 0
+#endif
+#endif
+
 #if RCT_DEV
 #define RCT_IF_DEV(...) __VA_ARGS__
 #else
diff --git a/React/DevSupport/RCTPackagerClient.h b/React/DevSupport/RCTPackagerClient.h
index 41cb7b645..4b070aa9b 100644
--- a/React/DevSupport/RCTPackagerClient.h
+++ b/React/DevSupport/RCTPackagerClient.h
@@ -16,11 +16,16 @@
 
 extern const int RCT_PACKAGER_CLIENT_PROTOCOL_VERSION;
 
-@protocol RCTPackagerClientMethod
+@protocol RCTPackagerClientMethod <NSObject>
 
 - (void)handleRequest:(id)params withResponder:(RCTPackagerClientResponder *)responder;
 - (void)handleNotification:(id)params;
 
+@optional
+
+/** By default object will receive its methods on the main queue, unless this method is overriden. */
+- (dispatch_queue_t)methodQueue;
+
 @end
 
 @interface RCTPackagerClientResponder : NSObject
diff --git a/React/DevSupport/RCTPackagerConnection.h b/React/DevSupport/RCTPackagerConnection.h
index c31a64cfd..ed8c951bb 100644
--- a/React/DevSupport/RCTPackagerConnection.h
+++ b/React/DevSupport/RCTPackagerConnection.h
@@ -13,19 +13,31 @@
 
 #if RCT_DEV
 
+NS_ASSUME_NONNULL_BEGIN
+
 @class RCTBridge;
 @protocol RCTPackagerClientMethod;
 @protocol RCTPackagerConnectionConfig;
 
 /**
- * Encapsulates connection to React Native packager
+ * Encapsulates connection to React Native packager.
+ * Dispatches messages from websocket to message handlers that must implement
+ * <RCTPackagerClientMethod> protocol.
+ * Message dispatch is performed on the main queue, unless message handler
+ * provides its own queue by overriding "methodQueue" method.
  */
 @interface RCTPackagerConnection : NSObject
 
++ (void)checkDefaultConnectionWithCallback:(void (^)(BOOL isRunning))callback
+                                     queue:(dispatch_queue_t)queue;
+
 + (instancetype)connectionForBridge:(RCTBridge *)bridge;
 - (instancetype)initWithConfig:(id<RCTPackagerConnectionConfig>)config;
 - (void)addHandler:(id<RCTPackagerClientMethod>)handler forMethod:(NSString *)name;
+- (void)stop;
 
 @end
 
+NS_ASSUME_NONNULL_END
+
 #endif
diff --git a/React/DevSupport/RCTPackagerConnection.m b/React/DevSupport/RCTPackagerConnection.m
index 8cb79b6c6..5b16bb9a2 100644
--- a/React/DevSupport/RCTPackagerConnection.m
+++ b/React/DevSupport/RCTPackagerConnection.m
@@ -13,6 +13,7 @@
 
 #import <React/RCTAssert.h>
 #import <React/RCTBridge.h>
+#import <React/RCTBundleURLProvider.h>
 #import <React/RCTConvert.h>
 #import <React/RCTDefines.h>
 #import <React/RCTLog.h>
@@ -26,6 +27,16 @@
 
 #if RCT_DEV
 
+static dispatch_queue_t RCTPackagerConnectionQueue()
+{
+  static dispatch_queue_t queue;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    queue = dispatch_queue_create("com.facebook.RCTPackagerConnectionQueue", DISPATCH_QUEUE_SERIAL);
+  });
+  return queue;
+};
+
 @interface RCTPackagerConnection () <RCTWebSocketProtocolDelegate>
 @end
 
@@ -35,6 +46,29 @@
   NSMutableDictionary<NSString *, id<RCTPackagerClientMethod>> *_handlers;
 }
 
++ (void)checkDefaultConnectionWithCallback:(void (^)(BOOL isRunning))callback
+                                     queue:(dispatch_queue_t)queue
+{
+  RCTBundleURLProvider *const settings = [RCTBundleURLProvider sharedSettings];
+  NSURLComponents *components = [NSURLComponents new];
+  components.scheme = @"http";
+  components.host = settings.jsLocation ?: @"localhost";
+  components.port = @(kRCTBundleURLProviderDefaultPort);
+  components.path = @"/status";
+  [NSURLConnection sendAsynchronousRequest:[NSURLRequest requestWithURL:components.URL]
+                                     queue:[NSOperationQueue mainQueue]
+                         completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
+                           NSString *const status = data != nil
+                             ? [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]
+                             : nil;
+                           BOOL isRunning = [status isEqualToString:@"packager-status:running"];
+
+                           dispatch_async(queue, ^{
+                             callback(isRunning);
+                           });
+                         }];
+}
+
 + (instancetype)connectionForBridge:(RCTBridge *)bridge
 {
   RCTPackagerConnectionBridgeConfig *config = [[RCTPackagerConnectionBridgeConfig alloc] initWithBridge:bridge];
@@ -46,7 +80,6 @@
   if (self = [super init]) {
     _packagerURL = [config packagerURL];
     _handlers = [[config defaultPackagerMethods] mutableCopy];
-
     [self connect];
   }
   return self;
@@ -70,19 +103,35 @@
   }
 
   NSString *key = [url absoluteString];
-  RCTReconnectingWebSocket *webSocket = socketConnections[key];
-  if (!webSocket) {
-    webSocket = [[RCTReconnectingWebSocket alloc] initWithURL:url];
-    [webSocket start];
-    socketConnections[key] = webSocket;
+  _socket = socketConnections[key];
+  if (!_socket) {
+    _socket = [[RCTReconnectingWebSocket alloc] initWithURL:url];
+    _socket.delegateDispatchQueue = RCTPackagerConnectionQueue();
+    [_socket start];
+    socketConnections[key] = _socket;
   }
 
-  webSocket.delegate = self;
+  _socket.delegate = self;
 }
 
+- (void)stop
+{
+  [_socket stop];
+}
+
+
 - (void)addHandler:(id<RCTPackagerClientMethod>)handler forMethod:(NSString *)name
 {
-  _handlers[name] = handler;
+  @synchronized(self) {
+    _handlers[name] = handler;
+  }
+}
+
+- (id<RCTPackagerClientMethod>)handlerForMethod:(NSString *)name
+{
+  @synchronized(self) {
+    return _handlers[name];
+  }
 }
 
 static BOOL isSupportedVersion(NSNumber *version)
@@ -95,10 +144,6 @@ static BOOL isSupportedVersion(NSNumber *version)
 
 - (void)webSocket:(RCTSRWebSocket *)webSocket didReceiveMessage:(id)message
 {
-  if (!_handlers) {
-    return;
-  }
-
   NSError *error = nil;
   NSDictionary<NSString *, id> *msg = RCTJSONParse(message, &error);
 
@@ -112,7 +157,7 @@ static BOOL isSupportedVersion(NSNumber *version)
     return;
   }
 
-  id<RCTPackagerClientMethod> methodHandler = _handlers[msg[@"method"]];
+  id<RCTPackagerClientMethod> methodHandler = [self handlerForMethod:msg[@"method"]];
   if (!methodHandler) {
     if (msg[@"id"]) {
       NSString *errorMsg = [NSString stringWithFormat:@"%@ no handler found for method %@", [self class], msg[@"method"]];
@@ -123,13 +168,19 @@ static BOOL isSupportedVersion(NSNumber *version)
     return; // If it was a broadcast then we ignore it gracefully
   }
 
-  if (msg[@"id"]) {
-    [methodHandler handleRequest:msg[@"params"]
-                   withResponder:[[RCTPackagerClientResponder alloc] initWithId:msg[@"id"]
-                                                                         socket:webSocket]];
-  } else {
-    [methodHandler handleNotification:msg[@"params"]];
-  }
+  dispatch_queue_t methodQueue = [methodHandler respondsToSelector:@selector(methodQueue)]
+    ? [methodHandler methodQueue]
+    : dispatch_get_main_queue();
+
+  dispatch_async(methodQueue, ^{
+    if (msg[@"id"]) {
+      [methodHandler handleRequest:msg[@"params"]
+                     withResponder:[[RCTPackagerClientResponder alloc] initWithId:msg[@"id"]
+                                                                           socket:webSocket]];
+    } else {
+      [methodHandler handleNotification:msg[@"params"]];
+    }
+  });
 }
 
 - (void)webSocketDidOpen:(RCTSRWebSocket *)webSocket
diff --git a/React/DevSupport/RCTPackagerConnectionBridgeConfig.h b/React/DevSupport/RCTPackagerConnectionBridgeConfig.h
index 0e8d3728e..afd02d51c 100644
--- a/React/DevSupport/RCTPackagerConnectionBridgeConfig.h
+++ b/React/DevSupport/RCTPackagerConnectionBridgeConfig.h
@@ -11,6 +11,8 @@
 
 #if RCT_DEV // Only supported in dev mode
 
+NS_ASSUME_NONNULL_BEGIN
+
 @class RCTBridge;
 
 @interface RCTPackagerConnectionBridgeConfig : NSObject <RCTPackagerConnectionConfig>
@@ -19,4 +21,6 @@
 
 @end
 
+NS_ASSUME_NONNULL_END
+
 #endif
diff --git a/React/DevSupport/RCTPackagerConnectionBridgeConfig.m b/React/DevSupport/RCTPackagerConnectionBridgeConfig.m
index 4c1978187..97d78f00b 100644
--- a/React/DevSupport/RCTPackagerConnectionBridgeConfig.m
+++ b/React/DevSupport/RCTPackagerConnectionBridgeConfig.m
@@ -9,7 +9,10 @@
 
 #import "RCTPackagerConnectionBridgeConfig.h"
 
+#import <objc/runtime.h>
+
 #import <React/RCTBridge.h>
+#import <React/RCTBundleURLProvider.h>
 
 #import "RCTJSEnvironment.h"
 #import "RCTReloadPackagerMethod.h"
@@ -18,38 +21,44 @@
 #if RCT_DEV // Only supported in dev mode
 
 @implementation RCTPackagerConnectionBridgeConfig {
-  RCTBridge *_bridge;
+  id<RCTJSEnvironment> _jsEnvironment;
+  RCTReloadPackagerMethodBlock _reloadCommand;
+  NSURL *_sourceURL;
 }
 
 - (instancetype)initWithBridge:(RCTBridge *)bridge
 {
   if (self = [super init]) {
-    _bridge = bridge;
+    _jsEnvironment = bridge;
+    _sourceURL = [bridge.bundleURL copy];
+    __weak RCTBridge *weakBridge = bridge;
+    _reloadCommand = ^(id params) {
+      if (params != (id)kCFNull && [params[@"debug"] boolValue]) {
+        weakBridge.executorClass = objc_lookUpClass("RCTWebSocketExecutor");
+      }
+      [weakBridge reload];
+    };
   }
   return self;
 }
 
 - (NSURL *)packagerURL
 {
-  NSString *host = [_bridge.bundleURL host];
-  NSString *scheme = [_bridge.bundleURL scheme];
-  if (!host) {
-    host = @"localhost";
-    scheme = @"http";
-  }
-
-  NSNumber *port = [_bridge.bundleURL port];
-  if (!port) {
-    port = @8081; // Packager default port
-  }
-  return [NSURL URLWithString:[NSString stringWithFormat:@"%@://%@:%@/message?role=ios-rn-rctdevmenu", scheme, host, port]];
+  NSURLComponents *components = [NSURLComponents new];
+  NSString *host = [_sourceURL host];
+  components.host = host ?: @"localhost";
+  components.scheme = host ? [_sourceURL scheme] : @"http";
+  components.port = [_sourceURL port] ?: @(kRCTBundleURLProviderDefaultPort);
+  components.path = @"/message";
+  components.queryItems = @[[NSURLQueryItem queryItemWithName:@"role" value:@"ios-rn-rctdevmenu"]];
+  return components.URL;
 }
 
 - (NSDictionary<NSString *, id<RCTPackagerClientMethod>> *)defaultPackagerMethods
 {
   return @{
-           @"reload": [[RCTReloadPackagerMethod alloc] initWithBridge:_bridge],
-           @"pokeSamplingProfiler": [[RCTSamplingProfilerPackagerMethod alloc] initWithJSEnvironment:_bridge]
+           @"reload": [[RCTReloadPackagerMethod alloc] initWithReloadCommand:_reloadCommand callbackQueue:dispatch_get_main_queue()],
+           @"pokeSamplingProfiler": [[RCTSamplingProfilerPackagerMethod alloc] initWithJSEnvironment:_jsEnvironment]
            };
 }
 
diff --git a/React/DevSupport/RCTPackagerConnectionConfig.h b/React/DevSupport/RCTPackagerConnectionConfig.h
index da9461dd0..090bede5f 100644
--- a/React/DevSupport/RCTPackagerConnectionConfig.h
+++ b/React/DevSupport/RCTPackagerConnectionConfig.h
@@ -11,6 +11,8 @@
 
 #if RCT_DEV // Only supported in dev mode
 
+NS_ASSUME_NONNULL_BEGIN
+
 @protocol RCTPackagerClientMethod;
 
 @protocol RCTPackagerConnectionConfig
@@ -20,4 +22,6 @@
 
 @end
 
+NS_ASSUME_NONNULL_END
+
 #endif
diff --git a/React/DevSupport/RCTReloadPackagerMethod.h b/React/DevSupport/RCTReloadPackagerMethod.h
index cd157edc6..d19fa6553 100644
--- a/React/DevSupport/RCTReloadPackagerMethod.h
+++ b/React/DevSupport/RCTReloadPackagerMethod.h
@@ -13,10 +13,16 @@
 
 #if RCT_DEV // Only supported in dev mode
 
+NS_ASSUME_NONNULL_BEGIN
+
+typedef void (^RCTReloadPackagerMethodBlock)(id);
+
 @interface RCTReloadPackagerMethod : NSObject <RCTPackagerClientMethod>
 
-- (instancetype)initWithBridge:(RCTBridge *)bridge;
+- (instancetype)initWithReloadCommand:(RCTReloadPackagerMethodBlock)block callbackQueue:(dispatch_queue_t)callbackQueue;
 
 @end
 
+NS_ASSUME_NONNULL_END
+
 #endif
diff --git a/React/DevSupport/RCTReloadPackagerMethod.m b/React/DevSupport/RCTReloadPackagerMethod.m
index 1135d0c79..317daec42 100644
--- a/React/DevSupport/RCTReloadPackagerMethod.m
+++ b/React/DevSupport/RCTReloadPackagerMethod.m
@@ -9,20 +9,20 @@
 
 #import "RCTReloadPackagerMethod.h"
 
-#import <objc/runtime.h>
-
 #import "RCTBridge.h"
 
 #if RCT_DEV // Only supported in dev mode
 
 @implementation RCTReloadPackagerMethod {
-  __weak RCTBridge *_bridge;
+  RCTReloadPackagerMethodBlock _block;
+  dispatch_queue_t _callbackQueue;
 }
 
-- (instancetype)initWithBridge:(RCTBridge *)bridge
+- (instancetype)initWithReloadCommand:(RCTReloadPackagerMethodBlock)block callbackQueue:(dispatch_queue_t)callbackQueue
 {
   if (self = [super init]) {
-    _bridge = bridge;
+    _block = [block copy];
+    _callbackQueue = callbackQueue;
   }
   return self;
 }
@@ -34,10 +34,12 @@
 
 - (void)handleNotification:(id)params
 {
-  if (![params isEqual:[NSNull null]] && [params[@"debug"] boolValue]) {
-    _bridge.executorClass = objc_lookUpClass("RCTWebSocketExecutor");
-  }
-  [_bridge reload];
+  _block(params);
+}
+
+- (dispatch_queue_t)methodQueue
+{
+  return _callbackQueue;
 }
 
 @end
diff --git a/React/Modules/RCTDevSettings.mm b/React/Modules/RCTDevSettings.mm
index 8e8386ff0..964b3dca9 100644
--- a/React/Modules/RCTDevSettings.mm
+++ b/React/Modules/RCTDevSettings.mm
@@ -36,8 +36,6 @@ static NSString *const kRCTDevSettingStartSamplingProfilerOnLaunch = @"startSamp
 
 static NSString *const kRCTDevSettingsUserDefaultsKey = @"RCTDevMenu";
 
-#define ENABLE_PACKAGER_CONNECTION RCT_DEV && __has_include("RCTPackagerConnection.h")
-
 #if ENABLE_PACKAGER_CONNECTION
 #import "RCTPackagerConnection.h"
 #endif