Not able to start MySQL service in Ubuntu 20.10 - mysql

Question

Issue Details:
I was running MySQL v8 on one of my Raspberry Pi 4 (8 GB) for a few months, however the I am unable to start mysql using sudo service mysql start since morning and receiving below error message:
Job for mysql.service failed because the control process exited with error code.
See "systemctl status mysql.service" and "journalctl -xe" for details.
Troubleshooting & Analysis
Re-installed MySQL 8
Tried to start the MySQL service using the above command, the service started without any issues.
However, when I updated the data directory from /etc/mysql/mysql.conf.d/mysqld.cnf file, the issue crept up again.
Does this tell me that there could be an issue on the the data directory ? Any solution to recover from this scenario ?
Execution Result: systemctl status mysql.service
mysql.service - MySQL Community Server
Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Tue 2021-02-02 18:08:10 IST; 1min 16s ago
Process: 3285 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
Process: 3294 ExecStart=/usr/sbin/mysqld (code=exited, status=2)
Main PID: 3294 (code=exited, status=2)
Status: "Server startup in progress"
error.log
2021-02-02T12:38:03.012089Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.23-0ubuntu0.20.10.1) starting as process 3185
2021-02-02T12:38:03.059589Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2021-02-02T12:38:03.596555Z 1 [ERROR] [MY-013183] [InnoDB] Assertion failure: fil0fil.cc:10815:initial_fsize == (file->size * phy_page_size) thread 281473363472416
InnoDB: We intentionally generate a memory trap.
InnoDB: Submit a detailed bug report to http://bugs.mysql.com.
InnoDB: If you get repeated assertion failures or crashes, even
InnoDB: immediately after the mysqld startup, there may be
InnoDB: corruption in the InnoDB tablespace. Please refer to
InnoDB: http://dev.mysql.com/doc/refman/8.0/en/forcing-innodb-recovery.html
InnoDB: about forcing recovery.
12:38:03 UTC - mysqld got signal 6 ;
Most likely, you have hit a bug, but this error can also be caused by malfunctioning hardware.
Thread pointer: 0xaaaadfc38ef0
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = ffff9fd7e690 thread_stack 0x46000
/usr/sbin/mysqld(my_print_stacktrace(unsigned char const*, unsigned long)+0x44) [0xaaaaceb08ae4]
/usr/sbin/mysqld(handle_fatal_signal+0x294) [0xaaaacdd1e484]
linux-vdso.so.1(__kernel_rt_sigreturn+0) [0xffffacbaf5d8]
/lib/aarch64-linux-gnu/libc.so.6(gsignal+0xd8) [0xffffac24ef58]
/lib/aarch64-linux-gnu/libc.so.6(abort+0xf4) [0xffffac23b50c]
/usr/sbin/mysqld(ut_dbg_assertion_failed(char const*, char const*, unsigned long)+0x26c) [0xaaaacedb993c]
/usr/sbin/mysqld(fil_tablespace_redo_extend(unsigned char*, unsigned char const*, page_id_t const&, unsigned long, bool)+0x4a8) [0xaaaaceeedd68]
/usr/sbin/mysqld(+0x1e79ba0) [0xaaaacec9aba0]
/usr/sbin/mysqld(+0x1e7aa44) [0xaaaacec9ba44]
/usr/sbin/mysqld(+0x1e7f670) [0xaaaaceca0670]
/usr/sbin/mysqld(recv_recovery_from_checkpoint_start(log_t&, unsigned long)+0x580) [0xaaaaceca1570]
/usr/sbin/mysqld(srv_start(bool)+0x1e68) [0xaaaaced6f7c8]
/usr/sbin/mysqld(+0x1dc8154) [0xaaaacebe9154]
/usr/sbin/mysqld(dd::bootstrap::DDSE_dict_init(THD*, dict_init_mode_t, unsigned int)+0x6c) [0xaaaace9205fc]
/usr/sbin/mysqld(dd::upgrade_57::do_pre_checks_and_initialize_dd(THD*)+0x164) [0xaaaacead8224]
/usr/sbin/mysqld(+0xf9d874) [0xaaaacddbe874]
/usr/sbin/mysqld(+0x21b9d84) [0xaaaacefdad84]
/lib/aarch64-linux-gnu/libpthread.so.0(+0x7f74) [0xffffac64ff74]
/lib/aarch64-linux-gnu/libc.so.6(+0xd73dc) [0xffffac2ee3dc]
Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (0): is an invalid pointer
Connection ID (thread ID): 1
Status: NOT_KILLED
Execution Result: sudo service mysql status
systemd[1]: mysql.service: Scheduled restart job, restart counter is at 5.
systemd[1]: Stopped MySQL Community Server.
systemd[1]: mysql.service: Start request repeated too quickly.
systemd[1]: mysql.service: Failed with result 'exit-code'.
systemd[1]: Failed to start MySQL Community Server.

Answer 1

It's a directory permission issue, make sure your directory is owned by mysql, and permission set to drwxr-x--- , you can do this by
chown mysql:mysql "data-dir"
chmod 760 "data-dir"