At least one JAR was scanned for TLDs yet contained no TLDs

Question

I keep getting this on tomcat 7.30 (eclipse juno)

At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.

Well I went at conf\logging.properties and turned all INFO to FINE and uncommented the line

# To see debug messages in TldLocationsCache, uncomment the following line: org.apache.jasper.compiler.TldLocationsCache.level = FINE 

And I still see At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging...

So what should I do to see those jars ?

Logs location :

The tomcat logs are in $CATALINA_HOME\logs\catalina.yyyy-mm-dd.log. Eclipse prints them in the console - if you want to have your console logged you must

In the servers tab, double-click on the Tomcat Server. You will get a screen called Overview. Click on "Open launch configuration". Click on the "Common" tab. Towards the bottom of the screen you can check the "File" checkbox and then specify a file that can be used to log your console (catalina.out) output. Finally, restart the Tomcat server.

Answer 1

If one wants to have the conf\logging.properties read one must (see also here) dump this file into the Servers\Tomcat v7.0 Server at localhost-config\ folder and then add the lines :

-Djava.util.logging.config.file="${workspace_loc}\Servers\Tomcat v7.0 Server at localhost-config\logging.properties" -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager

to the VM arguments of the launch configuration one is using.

This may have taken a restart or two (or not) but finally I saw in the console in bright red :

FINE: No TLD files were found in [file:/C:/Dropbox/eclipse_workspaces/javaEE/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/ted2012/WEB-INF/lib/logback-classic-1.0.7.jar]. Consider adding the JAR to the tomcat.util.scan.DefaultJarScanner.jarsToSkip or org.apache.catalina.startup.TldConfig.jarsToSkip property in CATALINA_BASE/conf/catalina.properties file. //etc

I still don't know when exactly this FINE warning appears - does not appear immediately on tomcat launch EDIT: from the comment by @Stephan: "The FINE warning appears each time any change is done in the JSP file".

---

Bonus: To make the warning go away add in catalina.properties :

# Additional JARs (over and above the default JARs listed above) to skip when # scanning for TLDs. The list must be a comma separated list of JAR file names. org.apache.catalina.startup.TldConfig.jarsToSkip=logback-classic-1.0.7.jar,\ joda-time-2.1.jar,joda-time-2.1-javadoc.jar,mysql-connector-java-5.1.24-bin.jar,\ logback-core-1.0.7.jar,javax.servlet.jsp.jstl-api-1.2.1.jar