Horizon become inaccessible after upgrading to RHEL 7.4

Issue

• Horizon become inaccessible after upgrading to RHEL 7.4
• Following errors will be output in /var/log/httpd/horizon_error.log

[Fri Aug 04 05:13:50.715579 2017] [core:error] [pid 21870] [client 10.68.5.20:55062] Script timed out before returning headers: django.wsgi
[Fri Aug 04 05:16:47.809959 2017] [core:error] [pid 21875] [client 10.68.5.20:54918] End of script output before headers: django.wsgi
[Fri Aug 04 05:16:51.843249 2017] [core:error] [pid 21820] [client 10.68.5.20:55034] End of script output before headers: django.wsgi

• Eventually the request will timeout