Mysql won't start anymore [closed] - mysql

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I wanted to check out my logserver again, but all of sudden i get this message when i visit the url:
I am running on ubuntu xenial
FATAL: Cannot connect to MySQL server on 'localhost'. Please make sure you have specified a valid MySQL database name in 'include/config.php'
when i do journalctl -xe i get the following message:
-- Unit mysql.service has begun starting up.
Jun 15 19:26:12 arjanlog audit[3665]: AVC apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/proc/3665/status" pid=3665 comm="mysqld" requested_mask="r" denied_mask="r" fsuid=112 ouid=112
Jun 15 19:26:12 arjanlog audit[3665]: AVC apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/sys/devices/system/node/" pid=3665 comm="mysqld" requested_mask="r" denied_mask="r" fsuid=112 ouid=0
Jun 15 19:26:12 arjanlog audit[3665]: AVC apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/proc/3665/status" pid=3665 comm="mysqld" requested_mask="r" denied_mask="r" fsuid=112 ouid=112
Jun 15 19:26:12 arjanlog kernel: audit: type=1400 audit(1497547572.504:69): apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld"
name="/proc/3665/status" pid=3665 comm="mysqld" requested_mask="r" denied_m
Jun 15 19:26:12 arjanlog kernel: audit: type=1400 audit(1497547572.504:70): apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/sys/devices/system/node/" pid=3665 comm="mysqld" requested_mask="r"
Jun 15 19:26:12 arjanlog kernel: audit: type=1400 audit(1497547572.504:71): apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/proc/3665/status" pid=3665 comm="mysqld" requested_mask="r" denied_m
Jun 15 19:26:12 arjanlog systemd[1]: mysql.service: Main process exited, code=exited, status=1/FAILURE

Answer 1

I had this problem too and solved it by fixing the apparmor configuration file at /etc/apparmor.d/usr.sbin.mysqld. I added these lines:
/proc/*/status r,
/sys/devices/system/node/ r,
/sys/devices/system/node/node0/meminfo r,
Your journalctl -xe output shows the files MySQL needs permission to use. You can also look in /var/log/syslog:
Jun 15 19:26:12 arjanlog audit[3665]: AVC apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/proc/3665/status" pid=3665 comm="mysqld" requested_mask="r" denied_mask="r" fsuid=112 ouid=112
Jun 15 19:26:12 arjanlog audit[3665]: AVC apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/sys/devices/system/node/" pid=3665 comm="mysqld" requested_mask="r" denied_mask="r" fsuid=112 ouid=0
Jun 15 19:26:12 arjanlog audit[3665]: AVC apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/proc/3665/status" pid=3665 comm="mysqld" requested_mask="r" denied_mask="r" fsuid=112 ouid=112
That means that /usr/sbin/mysqld was DENIED trying to open /proc/3665/status and /sys/devices/system/node/ for reading (r).
Note that in the apparmor config file the trailing slash in /sys/devices/system/node/ is necessary, so don't leave it off!

Answer 2

It may not be necessary to stop apparmor entirely. It should be sufficient brute force to disable apparmor for mysqld, if you don't want to track down the core issue:
ln -s /etc/apparmor.d/usr.sbin.mysqld /etc/apparmor.d/disable/usr.sbin.mysqld

Answer 3

For me the error was that the mysql database got corrupted. I could see that when I went to logs /var/log/mysql/error.log and it showed an error:
InnoDB: Database was not shutdown normally!
There were some solutions out there which someone could use like table corruption issue
But it didn't work for me as I wasn't able to start a server in WRITE mode in order to solve the issue.
I managed to solve the issue by creating a copy of directory /var/lib/mysql - I copied to mysql.old and then deleted the mysql directory.
Then I called a command in terminal:
sudo mysqld --initialize --initialize-insecure
To generate a new mysql directory
I have then changed permissions of new directory by changing the user and group of mysql directory to user: mysql and group: mysql. Use chown command:
sudo chown -R mysql:mysql /var/lib/mysql
Then I called command:
sudo mysql -u root
and changed password with:
SET PASSWORD FOR root#'localhost' = PASSWORD('newpassword');
And then restarted mysql server:
sudo service mysql restart
And everything worked.
Some of the commands that I have used along the way were (although not sure how much they contributed to fixing the issue):
sudo apt-get --reinstall install mysql-server-5.7

Answer 4

I read in another SO thread comment that the apparmor="DENIED" message probably isn't the reason that MySQL (or in my case MariaDB) wasn't starting, as it's only a warning.
In my case updating and upgrading apt-installed packages and rebooting the system solved the problem.
sudo apt-get dist-upgrade
sudo apt-get update
sudo apt-get upgrade
sudo reboot
Then you'll need to wait a few minutes while the system restarts and log back in and restart the service(s) with either service, systemctl and I think possibly /etc/system.d.
Then MariaDB was chugging away happily.
There's a good post on the various apt upgrade commands here, and I think that what update does is update the source lists.
I had found this command useful as well, when there were no log files in /var/log/mysql:
tail -f /var/log/syslog | grep mysql

Answer 5

I got this bug when I tried to move mysql file from /var/lib/mysql to somewhere else.
add config to /etc/apparmor.d/usr.sbin.mysqld didn't work for me
then i got this bug for ubuntu
it said:
sudo nano /etc/apparmor.d/usr.sbin.mysqld
line 25 after:
# Allow config access
/etc/mysql/** r,
-add line:
/etc/mysql/* r,
and it works for me:
add /etc/mysql/* r, to /etc/apparmor.d/usr.sbin.mysqld
run systemctl restart apparmor.service
and service mysql start

Answer 6

After I followed the instructions given in https://stackoverflow.com/a/45986591 I was still not able to make the MySql server run. I checked its logs via tail -30 /var/log/mysql/error.log . This line caught my attention 2019-05-21T04:46:03.462807Z 0 [ERROR] InnoDB: Cannot allocate memory for the buffer pool. By reading the previous line of code, I was that it was trying to allocate 128MB of memory. Then I checked my Memory status and it was only 111 Mb free. I stopped few programs (node servers) and restarted the MySql and it started working. Then i commented all the AppArmor entries I had entered and restarted AppArmor and MySql. MySql started without any errors. So I could conclude that MySql was not getting enough memory to get started.

Answer 7

solved by : sudo service apparmor teardown