Index: sddmthemeinstaller.cpp
===================================================================
--- sddmthemeinstaller.cpp
+++ sddmthemeinstaller.cpp
@@ -72,8 +72,9 @@
         KAuth::ExecuteJob *job = action.execute();
         bool rc = job->exec();
         if (!rc) {
-            KMessageBox::sorry(nullptr, i18n("Unable to install theme"), job->errorString());
-            qWarning() << job->error() << job->errorString();
+            QString errMessage = (job->error() != 0) ? job->errorString() : i18n("unknown error");
+            KMessageBox::sorry(nullptr, i18n("Unable to install theme, "), errMessage);
+            qWarning() << job->error() << errMessage;
             return -1;
         }