Let's say something like this is being returned when attempting to start a web server that is configured to use WebGate.

AH00526: Syntax error on line 44 of /var/www/html/webgate.httpd.conf:
Invalid command 'require', perhaps misspelled or defined by a module not included in the server configuration

Notice in this example that the error references line 44 of the /var/www/html/webgate.httpd.conf file. In this scenario, like 44 of the /var/www/html/webgate.httpd.conf file contains the following.

require valid-user

The "require" directive is provided by the mod_authz_core.so module. Ensure the web servers httpd.conf file has loaded the mod_authz_core.so module. In this example, the mod_authz_core.so file is located in the relative "modules" directory. For example, if the base installation directory of the Apache web server is /var/www, then the mod_authz_core.so file should be located at /var/www/modules/mod_authz_core.so.

LoadModule authz_core_module modules/mod_authz_core.so