Ytdyklly

In terminal I do:
sudo service mysql start

and I get:
Job for mysql.service failed because the control process exited with error code.
See "systemctl status mysql.service" and "journalctl -xe" for details.

systemctl status mysql.service gives me:

● mysql.service - MySQL Community Server Loaded: loaded
(/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)

Active: failed (Result: exit-code) since Wed 2018-10-31 22:05:05 UTC;
4s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html Process: 3592 ExecStart=/usr/sbin/mysqld (code=exited,
status=1/FAILURE) Process: 3542
ExecStartPre=/usr/share/mysql-8.0/mysql-systemd-start pre
(code=exited, status=0/SUCCESS) Main PID: 3592 (code=exited,
status=1/FAILURE) Status: "SERVER_BOOTING"
Error: 13 (Permission denied)

Oct 31 22:05:04 brawn systemd[1]: Starting MySQL Community Server...
Oct 31 22:05:05 brawn mysqld[3592]: 2018-10-31T22:05:05.104214Z 0
[System] [MY-010116] [Server] /usr/sbin/mysqld Oct 31 22:05:05 brawn
mysqld[3592]: mysqld: File './binlog.index' not found (OS errno 13 -
Permission denied) Oct 31 22:05:05 brawn mysqld[3592]:
2018-10-31T22:05:05.106057Z 0 [ERROR] [MY-010119] [Server] Aborting
Oct 31 22:05:05 brawn mysqld[3592]: 2018-10-31T22:05:05.106193Z 0
[System] [MY-010910] [Server] /usr/sbin/mysqld Oct 31 22:05:05 brawn
systemd[1]: mysql.service: Main process exited, code=exited,
status=1/FAILURE Oct 31 22:05:05 brawn systemd[1]: mysql.service:
Failed with result 'exit-code'. Oct 31 22:05:05 brawn systemd[1]:
Failed to start MySQL Community Server.

and journalctl -xe gives me:

-- Unit mysql.service has begun starting up.

Oct 31 22:05:04 brawn audit[3591]: AVC apparmor="STATUS" operation="profile_replace" info="same as current profi

Oct 31 22:05:04 brawn kernel: audit: type=1400 audit(1541023504.856:30): apparmor="STATUS" operation="profile_re

Oct 31 22:05:05 brawn mysqld[3592]: 2018-10-31T22:05:05.104214Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld

Oct 31 22:05:05 brawn mysqld[3592]: mysqld: File './binlog.index' not found (OS errno 13 - Permission denied)

Oct 31 22:05:05 brawn mysqld[3592]: 2018-10-31T22:05:05.106057Z 0 [ERROR] [MY-010119] [Server] Aborting

Oct 31 22:05:05 brawn mysqld[3592]: 2018-10-31T22:05:05.106193Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld

Oct 31 22:05:05 brawn systemd[1]: mysql.service: Main process exited, code=exited, status=1/FAILURE

Oct 31 22:05:05 brawn systemd[1]: mysql.service: Failed with result 'exit-code'.

Oct 31 22:05:05 brawn systemd[1]: Failed to start MySQL Community Server.

-- Subject: Unit mysql.service has failed

-- Defined-By: systemd

-- Support: http://www.ubuntu.com/support

-- 

-- Unit mysql.service has failed.

-- 

-- The result is RESULT.

Oct 31 22:05:05 brawn sudo[3512]: pam_unix(sudo:session): session closed for user root

Im quite new to Ubuntu and MySql, but I believe this issue is that for some reason MySql can no longer access './binlog.index', am I on the right track and how do I fix this?

I did try sudo find / -name binlog.index which gave me one result:

/var/lib/mysql/binlog.index

But how do I for it? what permission is required?

I ran sudo chown -R mysql:mysql /var/lib/mysql to give the mysql user permission on this folder, but do let me know if I have done the wrong thing.

For me the issue was caused by the custom values that I had added to my.cnf:

#query_cache_size = 0

#query_cache_type = 0

#query_cache_limit = 2M

#sort_buffer_size = 512K

#read_rnd_buffer_size = 512K

#tmp_table_size = 32M

#max_heap_table_size = 32M

#thread_pool_size = 24M

#innodb_log_file_size = 16M

As soon as those were commended out I didn't have any more issues.