diff --git a/realm/realm-library/src/main/cpp/io_realm_internal_objectstore_OsJavaNetworkTransport.cpp b/realm/realm-library/src/main/cpp/io_realm_internal_objectstore_OsJavaNetworkTransport.cpp
index 4dbd46d766..ce83bb31c3 100644
--- a/realm/realm-library/src/main/cpp/io_realm_internal_objectstore_OsJavaNetworkTransport.cpp
+++ b/realm/realm-library/src/main/cpp/io_realm_internal_objectstore_OsJavaNetworkTransport.cpp
@@ -34,7 +34,7 @@ JNIEXPORT void JNICALL Java_io_realm_internal_objectstore_OsJavaNetworkTransport
                                                                                                       jlong j_completion_block_ptr)
 {
     try {
-        auto& completion_block = *reinterpret_cast<std::function<void(const Response)>*>(j_completion_block_ptr);
+        util::UniqueFunction<void(const Response &)> &completion_block = *reinterpret_cast<util::UniqueFunction<void(const Response &)>*>(j_completion_block_ptr);
 
         // Read response
         static const JavaClass& response_class(JavaClassGlobalDef::network_transport_response_class());
diff --git a/realm/realm-library/src/main/cpp/io_realm_internal_objectstore_OsSubscriptionSet.cpp b/realm/realm-library/src/main/cpp/io_realm_internal_objectstore_OsSubscriptionSet.cpp
index 4268bcd1f8..cad9c2640c 100644
--- a/realm/realm-library/src/main/cpp/io_realm_internal_objectstore_OsSubscriptionSet.cpp
+++ b/realm/realm-library/src/main/cpp/io_realm_internal_objectstore_OsSubscriptionSet.cpp
@@ -74,7 +74,7 @@ JNIEXPORT jbyte JNICALL Java_io_realm_internal_objectstore_OsSubscriptionSet_nat
                 return io_realm_internal_objectstore_OsSubscriptionSet_STATE_VALUE_COMPLETE;
             case sync::SubscriptionSet::State::Error:
                 return io_realm_internal_objectstore_OsSubscriptionSet_STATE_VALUE_ERROR;
-            case sync::SubscriptionSet::State::Superceded:
+            case sync::SubscriptionSet::State::Superseded:
                 return io_realm_internal_objectstore_OsSubscriptionSet_STATE_VALUE_SUPERSEDED;
         }
     }
diff --git a/realm/realm-library/src/main/cpp/io_realm_mongodb_FunctionsImpl.cpp b/realm/realm-library/src/main/cpp/io_realm_mongodb_FunctionsImpl.cpp
index c27de9d41d..1fac6f13dc 100644
--- a/realm/realm-library/src/main/cpp/io_realm_mongodb_FunctionsImpl.cpp
+++ b/realm/realm-library/src/main/cpp/io_realm_mongodb_FunctionsImpl.cpp
@@ -45,14 +45,13 @@ Java_io_realm_mongodb_FunctionsImpl_nativeCallFunction(JNIEnv* env, jclass , jlo
         auto user = *reinterpret_cast<std::shared_ptr<SyncUser>*>(j_user_ptr);
 
         std::function<void(util::Optional<Bson>, util::Optional<app::AppError>)> callback = JavaNetworkTransport::create_result_callback(env, j_callback, success_mapper);
-
-        auto handler = [callback](util::Optional<app::AppError> error, util::Optional<Bson> response) {
+        util::UniqueFunction<void(util::Optional<Bson>&&, util::Optional<AppError>)> handler = [callback](const util::Optional<Bson>& response, const util::Optional<AppError>& error) {
             callback(response, error);
         };
 
         JStringAccessor name(env, j_name);
         BsonArray args(JniBsonProtocol::parse_checked(env, j_args_json, Bson::Type::Array, "BSON argument must be an BsonArray"));
-        app->call_function(user, name, args, handler);
+        app->call_function(user, name, args, std::move(handler));
     }
     CATCH_STD()
 }
diff --git a/realm/realm-library/src/main/cpp/io_realm_mongodb_sync_SyncSession.cpp b/realm/realm-library/src/main/cpp/io_realm_mongodb_sync_SyncSession.cpp
index 88f567c77b..1de42c5c66 100644
--- a/realm/realm-library/src/main/cpp/io_realm_mongodb_sync_SyncSession.cpp
+++ b/realm/realm-library/src/main/cpp/io_realm_mongodb_sync_SyncSession.cpp
@@ -289,7 +289,7 @@ JNIEXPORT jlong JNICALL Java_io_realm_mongodb_sync_SyncSession_nativeAddConnecti
                 throw std::runtime_error("An unexpected Error was thrown from Java. See LogCat");
             }
         };
-        uint64_t token = session->register_connection_change_callback(callback);
+        uint64_t token = session->register_connection_change_callback(std::move(callback));
         return static_cast<jlong>(token);
     }
     CATCH_STD()
diff --git a/realm/realm-library/src/main/cpp/java_network_transport.hpp b/realm/realm-library/src/main/cpp/java_network_transport.hpp
index 23afa4fbed..c903d0e7a4 100644
--- a/realm/realm-library/src/main/cpp/java_network_transport.hpp
+++ b/realm/realm-library/src/main/cpp/java_network_transport.hpp
@@ -42,8 +42,7 @@ struct JavaNetworkTransport : public app::GenericNetworkTransport {
         REALM_ASSERT_RELEASE_EX(m_send_request_method != nullptr, method_name, signature);
     }
 
-    void send_request_to_server(const app::Request request, std::function<void(const app::Response)> completionBlock)
-    {
+    void send_request_to_server(Request &&request, util::UniqueFunction<void(const Response &)> &&completionBlock) override {
         JNIEnv* env = JniUtils::get_env(true);
 
         // Setup method
@@ -82,7 +81,7 @@ struct JavaNetworkTransport : public app::GenericNetworkTransport {
                 static_cast<jlong>(request.timeout_ms),
                 request_headers,
                 jbody,
-                new std::function<void(const app::Response)>(std::move(completionBlock))
+                new util::UniqueFunction<void(const Response &)>(std::move(completionBlock))
         );
         env->DeleteLocalRef(jmethod);
         env->DeleteLocalRef(jurl);
diff --git a/realm/realm-library/src/main/cpp/realm-core b/realm/realm-library/src/main/cpp/realm-core
index 733f12702d..3ff90552f8 160000
--- a/realm/realm-library/src/main/cpp/realm-core
+++ b/realm/realm-library/src/main/cpp/realm-core
@@ -1 +1 @@
-Subproject commit 733f12702d16ab0d0c7fea0831a2aee5ca5c26db
+Subproject commit 3ff90552f81138a5d4339bf0572abd51144a4bb0