package mysql-server-8.0 8.0.23-0ubuntu0.20.04.1 failed to install/upgrade: can't create lock file /var/run/mysqld/mysqlx.sock.lock

[Rahul Choudhary]

Not sure what is the exact cause, please go through the logs

ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: mysql-server-8.0 8.0.23-0ubuntu0.20.04.1
ProcVersionSignature: Ubuntu 5.8.0-40.45~20.04.1-generic 5.8.18
Uname: Linux 5.8.0-40-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
Date: Sun Feb 7 10:40:26 2021
ErrorMessage: installed mysql-server-8.0 package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2020-11-07 (91 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
Logs.var.log.daemon.log:

MySQLConf.etc.mysql.conf.d.mysql.cnf: [mysql]
MySQLConf.etc.mysql.conf.d.mysqldump.cnf:
 [mysqldump]
 quick
 quote-names
 max_allowed_packet = 16M
MySQLVarLibDirListing: ['performance_schema', 'binlog.index', 'debian-5.7.flag', 'binlog.000067', 'binlog.000065', 'binlog.000068', 'binlog.000074', 'binlog.000062', 'binlog.000058', 'auto.cnf', 'ib_logfile0', 'client-key.pem', 'private_key.pem', 'ib_buffer_pool', 'binlog.000073', '#innodb_temp', 'client-cert.pem', 'binlog.000066', 'binlog.000072', 'binlog.000061', 'sys', '#ib_16384_0.dblwr', 'undo_001', 'binlog.000070', 'undo_002', 'ibdata1', 'binlog.000064', 'binlog.000060', 'mysql', 'server-cert.pem', 'binlog.000063', 'ca.pem', 'mysql.ibd', 'public_key.pem', 'binlog.000071', 'binlog.000069', 'binlog.000059', 'ib_logfile1', 'ca-key.pem', 'mysql_upgrade_info', 'trigger_db', 'ig_clone', '#ib_16384_1.dblwr', 'binlog.000057', 'server-key.pem']
ProcCmdline: BOOT_IMAGE=/boot/vmlinuz-5.8.0-40-generic root=UUID=f858c90e-3f68-4178-ac70-a4b95972506f ro quiet splash vt.handoff=7
Python3Details: /usr/bin/python3.8, Python 3.8.5, python3-minimal, 3.8.2-0ubuntu2
PythonDetails: N/A
RelatedPackageVersions:
 dpkg 1.19.7ubuntu3
 apt 2.0.4
SourcePackage: mysql-8.0
Title: package mysql-server-8.0 8.0.23-0ubuntu0.20.04.1 failed to install/upgrade: installed mysql-server-8.0 package post-installation script subprocess returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)

== Error Log ==
mysqld will log errors to /var/log/mysql/error.log
mysqld is running as pid 40931
Error: Unable to shut down server with process id 40931
[1mdpkg:[0m error processing package mysql-server-8.0 (--configure):
 installed mysql-server-8.0 package post-installation script subprocess
 returned error exit status 1

[MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.23-0ubuntu0.20.04.1) starting as process 40929
[MY-013576] [InnoDB] InnoDB initialization has started.
[MY-013577] [InnoDB] InnoDB initialization has ended.
[MY-011090] [Server] Data dictionary upgrading from version '80022' to '80023'.
[MY-013413] [Server] Data dictionary upgrade from version '80022' to '80023' completed.
[MY-011292] [Server] Plugin mysqlx reported: 'Preparation of I/O interfaces failed, X Protocol won't be accessible'
[MY-011300] [Server] Plugin mysqlx reported: 'Setup of socket: '/var/run/mysqld/mysqlx.sock' failed, can't create lock file /var/run/mysqld/mysqlx.sock.lock'
[MY-013381] [Server] Server upgrade from '80022' to '80023' started.
[MY-013381] [Server] Server upgrade from '80022' to '80023' completed.
[MY-010068] [Server] CA certificate ca.pem is self signed.
[MY-013602] [Server] Channel mysql_main configured to support TLS. Encrypted connections are now supported for this channel.
[MY-011810] [Server] Insecure configuration for --pid-file: Location '/tmp' in the path is accessible to all OS users. Consider choosing a different directory.
[MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.23-0ubuntu0.20.04.1' socket: '/tmp/tmp.tD6McUfLHO/mysqld.sock' port: 0 (Ubuntu).
[MY-013172] [Server] Received SHUTDOWN from user <via user signal>. Shutting down mysqld (Version: 8.0.23-0ubuntu0.20.04.1).
[MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.23-0ubuntu0.20.04.1) (Ubuntu).

[Bryce Harrington (bryce)]

The installation failure might have been due to:

 [MY-011300] [Server] Plugin mysqlx reported: 'Setup of socket: '/var/run/mysqld/mysqlx.sock' failed, can't create lock file /var/run/mysqld/mysqlx.sock.lock'

In the past there have been reports that apparmor profile settings cause these kinds of errors (see for example https://serverfault.com/questions/751277/mysql-daemon-lock-issue), although your apparmor config looks ok to me (I'm no apparmor guru though).