diff --git a/ReactAndroid/src/main/java/com/facebook/react/devsupport/BundleDeltaClient.java b/ReactAndroid/src/main/java/com/facebook/react/devsupport/BundleDeltaClient.java
index bdc6d084407..e035c976a52 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/devsupport/BundleDeltaClient.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/devsupport/BundleDeltaClient.java
@@ -105,6 +105,10 @@ public abstract class BundleDeltaClient {
           mPostCode = jsonReader.nextString().getBytes();
         } else if (name.equals("modules")) {
           numChangedModules += setModules(jsonReader, mModules);
+        } else if (name.equals("added")) {
+          numChangedModules += setModules(jsonReader, mModules);
+        } else if (name.equals("modified")) {
+          numChangedModules += setModules(jsonReader, mModules);
         } else if (name.equals("deleted")) {
           numChangedModules += removeModules(jsonReader, mModules);
         } else {
diff --git a/ReactCommon/cxxreact/JSDeltaBundleClient.cpp b/ReactCommon/cxxreact/JSDeltaBundleClient.cpp
index 86edf47c800..2f66e861eb4 100644
--- a/ReactCommon/cxxreact/JSDeltaBundleClient.cpp
+++ b/ReactCommon/cxxreact/JSDeltaBundleClient.cpp
@@ -26,6 +26,14 @@ namespace {
   }
 } // namespace
 
+void JSDeltaBundleClient::patchModules(const folly::dynamic *modules) {
+  for (const folly::dynamic pair : *modules) {
+    auto id = pair[0].getInt();
+    auto module = pair[1];
+    modules_.emplace(id, module.getString());
+  }
+}
+
 void JSDeltaBundleClient::patch(const folly::dynamic& delta) {
   auto const base = delta.get_ptr("base");
 
@@ -36,6 +44,11 @@ void JSDeltaBundleClient::patch(const folly::dynamic& delta) {
     auto const post = delta.get_ptr("post");
 
     startupCode_ = startupCode(pre, post);
+
+    const folly::dynamic *modules = delta.get_ptr("modules");
+    if (modules != nullptr) {
+      patchModules(modules);
+    }
   } else {
     const folly::dynamic *deleted = delta.get_ptr("deleted");
     if (deleted != nullptr) {
@@ -43,16 +56,25 @@ void JSDeltaBundleClient::patch(const folly::dynamic& delta) {
         modules_.erase(id.getInt());
       }
     }
-  }
 
-  const folly::dynamic *modules = delta.get_ptr("modules");
-  if (modules != nullptr) {
-    for (const folly::dynamic pair : *modules) {
-      auto id = pair[0].getInt();
-      auto module = pair[1];
-      modules_.emplace(id, module.getString());
+    // TODO T37123645 This is deprecated but necessary in order to support older
+    // versions of the Metro server.
+    const folly::dynamic *modules = delta.get_ptr("modules");
+    if (modules != nullptr) {
+      patchModules(modules);
+    }
+
+    const folly::dynamic *added = delta.get_ptr("added");
+    if (added != nullptr) {
+      patchModules(added);
+    }
+
+    const folly::dynamic *modified = delta.get_ptr("modified");
+    if (modified != nullptr) {
+      patchModules(modified);
     }
   }
+
 }
 
 JSModulesUnbundle::Module JSDeltaBundleClient::getModule(uint32_t moduleId) const {
diff --git a/ReactCommon/cxxreact/JSDeltaBundleClient.h b/ReactCommon/cxxreact/JSDeltaBundleClient.h
index 823beab076f..5ee2aba9ca7 100644
--- a/ReactCommon/cxxreact/JSDeltaBundleClient.h
+++ b/ReactCommon/cxxreact/JSDeltaBundleClient.h
@@ -27,6 +27,8 @@ public:
 private:
   std::unordered_map<uint32_t, std::string> modules_;
   std::string startupCode_;
+
+  void patchModules(const folly::dynamic *delta);
 };
 
 class JSDeltaBundleClientRAMBundle : public JSModulesUnbundle {
diff --git a/local-cli/server/util/debugger-ui/DeltaPatcher.js b/local-cli/server/util/debugger-ui/DeltaPatcher.js
index 7d7734f08e3..ed950295f6c 100644
--- a/local-cli/server/util/debugger-ui/DeltaPatcher.js
+++ b/local-cli/server/util/debugger-ui/DeltaPatcher.js
@@ -72,12 +72,17 @@
           modules: new Map(bundle.modules),
         };
       } else {
-        this._lastNumModifiedFiles =
-          bundle.modules.length + bundle.deleted.length;
+        // TODO T37123645 The former case is deprecated, but necessary in order to
+        // support older versions of the Metro bundler.
+        const modules = bundle.modules
+          ? bundle.modules
+          : bundle.added.concat(bundle.modified);
+
+        this._lastNumModifiedFiles = modules.length + bundle.deleted.length;
 
         this._lastBundle.revisionId = bundle.revisionId;
 
-        for (const [key, value] of bundle.modules) {
+        for (const [key, value] of modules) {
           this._lastBundle.modules.set(key, value);
         }