diff --git a/examples/cpp/request_reply/ServerApp.cpp b/examples/cpp/request_reply/ServerApp.cpp
index fe85a7c7555..598711673a1 100644
--- a/examples/cpp/request_reply/ServerApp.cpp
+++ b/examples/cpp/request_reply/ServerApp.cpp
@@ -208,6 +208,10 @@ void ServerApp::on_publication_matched(
     {
         request_reply_error("ServerApp", info.current_count_change
                 << " is not a valid value for PublicationMatchedStatus current count change");
+
+        // __FLAG__
+        throw std::runtime_error("ERROR");
+        /////////////////
     }
 }
 
@@ -241,6 +245,9 @@ void ServerApp::on_subscription_matched(
         request_reply_error("ServerApp",
                 info.current_count_change <<
                 " is not a valid value for SubscriptionMatchedStatus current count change");
+        // __FLAG__
+        throw std::runtime_error("ERROR");
+        /////////////////
     }
 }
 
diff --git a/src/cpp/rtps/builtin/discovery/participant/PDP.cpp b/src/cpp/rtps/builtin/discovery/participant/PDP.cpp
index 645fe9faa93..e3b83603c42 100644
--- a/src/cpp/rtps/builtin/discovery/participant/PDP.cpp
+++ b/src/cpp/rtps/builtin/discovery/participant/PDP.cpp
@@ -1279,8 +1279,8 @@ bool PDP::remove_remote_participant(
     ParticipantProxyData* pdata = nullptr;
 
     // Remove it from our vector of RTPSParticipantProxies
+    std::lock_guard<std::recursive_mutex> guardPDP(*mp_mutex);
     {
-        std::lock_guard<std::recursive_mutex> guardPDP(*mp_mutex);
         for (ResourceLimitedVector<ParticipantProxyData*>::iterator pit = participant_proxies_.begin();
                 pit != participant_proxies_.end(); ++pit)
         {