diff --git a/src/gui/dialogs/addon/manager.cpp b/src/gui/dialogs/addon/manager.cpp
index 8aef421760e..e2a4b84a539 100644
--- a/src/gui/dialogs/addon/manager.cpp
+++ b/src/gui/dialogs/addon/manager.cpp
@@ -932,6 +932,10 @@ void addon_manager::publish_addon(const addon_info& addon)
 		} else {
 			preferences::set_password(preferences::campaign_server(), cfg["author"], cfg["passphrase"]);
 		}
+	} else if(cfg["forum_auth"].to_bool()) {
+		// if the uploader's forum password is present in the _server.pbl
+		gui2::show_error_message(_("The passphrase attribute cannot be present when forum_auth is used."));
+		return;
 	}
 
 	if(!::image::exists(cfg["icon"].str())) {