503 Service Unavailable

Provider: Vultr

Virtualization Type: KVM

System: Ubuntu 18.04

Installation option: since during the installation.
there will be few option to choose,so please provide it as well.

OLS or Enterprise?
OLS

Installing from official server or mirror server?
official

Install Memcached extension for PHP?
yes

Install LiteSpeed Memcached?
yes

Install Memcached?
yes

Install Redis extension for PHP?
yes

Install Redis?
yes

Problem:
My server error http://prntscr.com/s5me12 and log http://prntscr.com/s5me7r http://prntscr.com/s5me9q

Can everyone help me? I think OLS has a problem. Thanks

Full Inodes /tmp and i reboot vps ubuntu → all site working but panel 503
Service Unavailable http://prntscr.com/s5ppu6

one of my domain is giving error 503

if i change the php version from backend 5.3 than it will start again,
but again start showing error after 2-3 days.
what is the problem