Squid Cache: Version 3.5.27Web Safety for Squid Proxy, version 5.2.0.210A-x86_64-linux-centos7
Workaround - in
/opt/websafety/var/console/squid/templates/squid/conf/access_controls.conf
at line 540 and several lines below you need to wrap it with {% autoescape off %}
and {% endautoescape %}
django template directives so that it looks like:
# advanced acl written as-is without autoescape
{% autoescape off %}
{% if acldefault.advanced_acl %}{{acldefault.advanced_acl}}
{% else %}# no advanced acls specified
{% endif %}
{% endautoescape %}
restart successful!