diff -Nru calibre-4.99.4+dfsg+really4.12.0/debian/changelog calibre-4.99.4+dfsg+really4.12.0/debian/changelog
--- calibre-4.99.4+dfsg+really4.12.0/debian/changelog	2020-04-10 14:56:10.000000000 -0400
+++ calibre-4.99.4+dfsg+really4.12.0/debian/changelog	2020-12-23 12:53:50.000000000 -0500
@@ -1,3 +1,11 @@
+calibre (4.99.4+dfsg+really4.12.0-1ubuntu1) focal; urgency=medium
+
+  * Fix error during startup (LP: #1898904)
+    - debian/patches/fix_cancel_attribute.patch: upstream patch to fix
+      unknown attribute error in src/calibre/utils/ipc/server.py.
+
+ -- Marc Deslauriers <marc.deslauriers@ubuntu.com>  Wed, 23 Dec 2020 12:53:50 -0500
+
 calibre (4.99.4+dfsg+really4.12.0-1build1) focal; urgency=medium
 
   * No-change rebuild against qtbase-abi-5-12-8.
diff -Nru calibre-4.99.4+dfsg+really4.12.0/debian/control calibre-4.99.4+dfsg+really4.12.0/debian/control
--- calibre-4.99.4+dfsg+really4.12.0/debian/control	2020-03-06 07:09:07.000000000 -0500
+++ calibre-4.99.4+dfsg+really4.12.0/debian/control	2020-12-23 12:53:50.000000000 -0500
@@ -70,7 +70,8 @@
  python3-routes,
  python3-zeroconf,
  xdg-utils,
-Maintainer: Norbert Preining <norbert@preining.info>
+Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
+XSBC-Original-Maintainer: Norbert Preining <norbert@preining.info>
 Uploaders: Martin Pitt <mpitt@debian.org>,
  Nicholas D Steeves <nsteeves@gmail.com>,
  YOKOTA Hiroshi <yokota.hgml@gmail.com>
diff -Nru calibre-4.99.4+dfsg+really4.12.0/debian/patches/fix_cancel_attribute.patch calibre-4.99.4+dfsg+really4.12.0/debian/patches/fix_cancel_attribute.patch
--- calibre-4.99.4+dfsg+really4.12.0/debian/patches/fix_cancel_attribute.patch	1969-12-31 19:00:00.000000000 -0500
+++ calibre-4.99.4+dfsg+really4.12.0/debian/patches/fix_cancel_attribute.patch	2020-12-23 12:53:47.000000000 -0500
@@ -0,0 +1,23 @@
+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 @@ def __init__(self, *args, **kwargs):
+             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.
diff -Nru calibre-4.99.4+dfsg+really4.12.0/debian/patches/series calibre-4.99.4+dfsg+really4.12.0/debian/patches/series
--- calibre-4.99.4+dfsg+really4.12.0/debian/patches/series	2020-03-06 07:09:07.000000000 -0500
+++ calibre-4.99.4+dfsg+really4.12.0/debian/patches/series	2020-12-23 12:53:47.000000000 -0500
@@ -115,3 +115,4 @@
 Hardening-Qt-code.patch
 disable-unrar-test
 Use-pyopenssl-instead-of-certgen.patch
+fix_cancel_attribute.patch