Not able to start task from my server

Hi Team,

I am not able to run any scan because start task option is not working neither from UI nor from the command line.
below are the specifications i have

Greenbone Security Assistant 8.0.0
OpenVAS Scanner 6.0.0
Linux localhost.localdomain 3.10.0-957.27.2.el7.x86_64 #1 SMP Mon Jul 29 17:46:05 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

CPU 1 core
Disk 100 GB

Please update to the more recent releases listed in GVM-10 (stable, initial release 2019-04-05) and try again.