The admin.conf file of the admin server is used to determine the location of the error log. By default, the admin.conf file will have the following.

ErrorLog logs/admin_error.log

With this configuration, the error log would be located at:

<web_server_root>/logs/admin_error.log

As the name implies, the admin_error.log will capture events classified as an error. Here is an example of an error in admin_error.log.

[Tue Mar 24 04:05:11.239998 2020] [:error] [pid 110535:tid 139637754234624] ac_util: Error changing Socket file owner, chgrp cmd error-> 1
[Tue Mar 24 04:05:11.240182 2020] [:error] [pid 110535:tid 139637754234624] ac_util: Severe error in Administration Server root process, Administration Server has been terminated
[Tue Mar 24 04:05:11.240187 2020] [:error] [pid 110535:tid 139637754234624] ac_util: Administration Server must be started from root id