From 20288dd4215846071dc6f2bbf9372378e7b4b13c Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Thu, 29 Mar 2018 19:14:15 +0530
Subject: [PATCH] ...

---
 src/calibre/gui2/ui.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/calibre/gui2/ui.py b/src/calibre/gui2/ui.py
index a5c5be1666..ce49ddbad2 100644
--- a/src/calibre/gui2/ui.py
+++ b/src/calibre/gui2/ui.py
@@ -972,7 +972,7 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin,  # {{{
         if write_settings:
             self.write_settings()
         self.check_messages_timer.stop()
-        if hasattr(self, 'update_checker'):
+        if getattr(self, 'update_checker', None):
             self.update_checker.shutdown()
         self.listener.close()
         self.job_manager.server.close()