The XWiki Logging Application works with the Logging Module to provide a dedicated UI in the wiki administration in order to easily retrieve and interpret XWiki logs. To access the application, click the  button to open the drawer menu, then on "Administer Wiki".

Next, click on "Logging" under "Other" in the accordion menu on the left

which will launch the list of registered XWiki loggers and the corresponding log level set for each of them.

An empty log level is equivalent to "default" meaning that the value is inherited from the logger of the parent. For instance, the parent of com.xpn.xwiki.plugin.watchlist.AutomaticWatchModeListener is com.xpn.xwiki.plugin.watchlist.

The 5 available log levels are:

• TRACE - designates finer-grained informational events than the DEBUG level.
• DEBUG - designates fine-grained informational events that are most useful to debug an application.
• INFO - designates informational messages that highlight the progress of the application at coarse-grained level.
• WARN - designates potentially harmful situations.
• ERROR - designates error events that might still allow the application to continue running.

To set the ERROR log level for the com.xpn.xwiki.plugin.watchlist logger which is by default empty, select "ERROR" from the "Actions" drop-down, then click on "Set". The new value should then appear in the "Level" column.

By default XWiki is configured to log everything on the console only. Tomcat will capture stdout and add logs to the "tomcat/logs/catalina.out" file on UNIX systems and to the "logs/catalina.<date>.log" file on Windows systems. Also, XWiki uses SLF4J for logging which allows the end user to plug in the desired logging framework at deployment time. To learn more about the SLF4J configuration file as well as other tips regarding logging configuration, go to the xwiki.org Logging documentation.