Unable to start MySQL on Ubuntu: AVC apparmor=”DENIED” operation=”open”

MySQL on Ubuntu fails to start. The following error messages are shown in the output of the journalctl -xecommand:

AVC apparmor=”DENIED” operation=”open” profile=”/usr/sbin/mysqld” name=”/proc/666999/status” pid=666999 comm=”mysqld” requested_mask=”r” denied_mask=”r” fsuid=124 ouid=124
AVC apparmor=”DENIED” operation=”open” profile=”/usr/sbin/mysqld” name=”/sys/devices/system/node/” pid=666999 comm=”mysqld” requested_mask=”r” denied_mask=”r” fsuid=124 ouid=0
audit: type=1400 audit(): apparmor=”DENIED” operation=”open” profile=”/usr/sbin/mysqld” name=”/proc/666999/status” pid=666999 comm=”mysqld” requested_mask=”r” denied_mask=”r” fsuid=124 ouid=124
audit: type=1400 audit(): apparmor=”DENIED” operation=”open” profile=”/usr/sbin/mysqld” name=”/sys/devices/system/node/” pid=666999 comm=”mysqld” requested_mask=”r” denied_mask=”r” fsuid=124 ouid=0

Cause

AppArmor is not properly configured.

Resolution

Add permissions for the objects reported in the lines that start with ‘name=‘ in the output to the file /etc/apparmor.d/usr.sbin.mysqld.

In this example, it is required to add r permissions to /proc/*/status and /sys/devices/system/node/. The paths may be different depending on the error messages.

1. Connect the server via SSH.
2. Open the file /etc/apparmor.d/usr.sbin.mysqld in a text editor (for example, vi editor) and add the lines below at the end of the /usr/sbin/mysqld section at the end of the file
   /usr/sbin/mysqld {
   …
   /proc/*/status r,
   /sys/devices/system/node/ r,
   /sys/devices/system/node/node*/meminfo r,
   /sys/devices/system/node/*/* r,
   /sys/devices/system/node/* r,
   …
   }
3. Reload AppArmor configuration for MySQL service:# apparmor_parser -r /etc/apparmor.d/usr.sbin.mysqld
4. Start MySQL server:# service mysql start

Or, Just in case if the steps above does not work, you can try the following steps:

Open File: /etc/apparmor.d/local/usr.sbin.mysqld

Add these lines:

/data/ r,
/data/** rwk,

systemctl restart apparmor

Hope this helps.