From 7b6416ac6522fc40f24f6baf3ca552b17a8b91d6 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sat, 2 May 2020 09:02:40 +0530
Subject: [PATCH] ...

---
 src/calibre/utils/ipc/server.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/calibre/utils/ipc/server.py b/src/calibre/utils/ipc/server.py
index a238dea531..cf8d558d88 100644
--- a/src/calibre/utils/ipc/server.py
+++ b/src/calibre/utils/ipc/server.py
@@ -107,7 +107,8 @@ if islinux:
             Listener.__init__(self, *args, **kwargs)
             # multiprocessing tries to call unlink even on abstract
             # named sockets, prevent it from doing so.
-            self._listener._unlink.cancel()
+            if self._listener._unlink is not None:
+                self._listener._unlink.cancel()
             # Prevent child processes from inheriting this socket
             # If we dont do this child processes not created by calibre, will
             # inherit this socket, preventing the calibre GUI from being restarted.