You’ll find the referenced log file in the same directory containing the log referencing the other log file. With a default installation of Tomcat, the directory is $CATALINA_HOME/logs. The log file containing the information referenced will usually be the one named with the hostname on which Tomcat is running. On a simple server (e.g. development environment) this is localhost.<datestamp>.log. The additional error information can be found in this log file at the same timestamp as the noted reference in the referring log file.