apparmor denied error

[nttec]

AVC apparmor="DENIED" operation="mount" info="failed flags match" error=-13 profile="lxc-140_</var/lib/lxc>" name="/" pid=37199 comm="(httpd)" flags="rw, rslave"
Jun 26 13:23:25 px1 kernel: audit: type=1400 audit(1561580605.876:129): apparmor="DENIED" operation="mount" info="failed flags match" error=-13 profile="lxc-140_</var/lib/lxc>" name="/" pid=37199 comm="(httpd)" flags="rw, rslave"

I am seeing a lot of this on my syslog, what does this mean?

 

[Alwin]

Appamor denied an action of the httpd service (CT 140). This is a security framework to protect your system.
https://pve.proxmox.com/pve-docs/chapter-pct.html