update-manager crashed with dbus.exceptions.DBusException in call_blocking(): org.freedesktop.DBus.Error.TimedOut: Failed to activate service 'org.debian.apt': timed out (service_start_timeout=25000ms)

When I turned on my computer, update-manager automatically opened because of the presence of updates. I started downloading these updates, I switched to Firefox to do something else in the meanwhile, update-manager apparently hanged and then I got this crash.

ProblemType: Crash
DistroRelease: Ubuntu 19.04
Package: update-manager 1:19.04.5
ProcVersionSignature: Ubuntu 5.0.0-15.16-generic 5.0.6
Uname: Linux 5.0.0-15-generic x86_64
ApportVersion: 2.20.10-0ubuntu27
Aptdaemon:
 giu 04 08:41:57 davide-K30AD-M31AD-M51AD AptDaemon[5285]: INFO: Initializing daemon
 giu 04 08:41:58 davide-K30AD-M31AD-M51AD org.debian.apt[859]: 08:41:57 AptDaemon [INFO]: Initializing daemon
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Tue Jun 4 08:41:59 2019
ExecutablePath: /usr/bin/update-manager
InstallationDate: Installed on 2018-06-18 (350 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
InterpreterPath: /usr/bin/python3.7
PackageArchitecture: all
ProcCmdline: /usr/bin/python3 /usr/bin/update-manager --no-update --no-focus-on-map
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=it_IT.UTF-8
 SHELL=/bin/bash
Python3Details: /usr/bin/python3.7, Python 3.7.3, python3-minimal, 3.7.3-1
PythonArgs: ['/usr/bin/update-manager', '--no-update', '--no-focus-on-map']
PythonDetails: /usr/bin/python2.7, Python 2.7.16, python-minimal, 2.7.16-1
SourcePackage: update-manager
Title: update-manager crashed with dbus.exceptions.DBusException in call_blocking(): org.freedesktop.DBus.Error.TimedOut: Failed to activate service 'org.debian.apt': timed out (service_start_timeout=25000ms)
UpgradeStatus: Upgraded to disco on 2019-04-18 (46 days ago)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
mtime.conffile..etc.apport.crashdb.conf: 2018-10-22T09:50:20.732763