diff --git a/src/colnod/colnodapi.cpp b/src/colnod/colnodapi.cpp
index f1a8419..f3cee3c 100644
--- a/src/colnod/colnodapi.cpp
+++ b/src/colnod/colnodapi.cpp
@@ -32,6 +32,7 @@ void ColnodAPI::downloadData(const Timestamp &time)
             if (!checkRequest(request)) {
                 qWarning(colnod) << "ERROR during calling" << request->url() << ", request unsuccessful";
                 mValid = false;
+                emit downloadDataFinished(nullptr);
             }
             else if (!checkResponse(request->responseData())) {
                 qWarning(colnod) << "Data from" << request->url() << "are invalid";
diff --git a/src/colnod/colnodapi.h b/src/colnod/colnodapi.h
index 77dd515..76c7bec 100644
--- a/src/colnod/colnodapi.h
+++ b/src/colnod/colnodapi.h
@@ -96,7 +96,7 @@ private:
 
 
 signals:
-    void downloadDataFinished(std::shared_ptr<Data> = nullptr);
+    void downloadDataFinished(std::shared_ptr<Data> = std::shared_ptr<Data>());
     void partOfDataReady(std::shared_ptr<Data> = std::shared_ptr<Data>());
     void partOfDataProcessFinished();
     void dataProcessFinished();