diff --git a/src/plugins/coreplugin/editormanager/editormanager.cpp b/src/plugins/coreplugin/editormanager/editormanager.cpp
index 0ce471f6da7..9591262b4a6 100644
--- a/src/plugins/coreplugin/editormanager/editormanager.cpp
+++ b/src/plugins/coreplugin/editormanager/editormanager.cpp
@@ -589,6 +589,8 @@ IEditor *EditorManagerPrivate::openEditor(EditorView *view, const QString &fileN
     QString errorString;
     if (!editor->open(&errorString, fn, realFn)) {
         QApplication::restoreOverrideCursor();
+        if (errorString.isEmpty())
+            errorString = tr("Could not open \"%1\": Unknown error").arg(realFn);
         QMessageBox::critical(ICore::mainWindow(), EditorManager::tr("File Error"), errorString);
         delete editor;
         return 0;