Can't turn off HtmlUnit logging messages

I too had issues with this.. The answer depends on what logging system commons-logging is using under the hood. (since common-logging is just a wrapper). See the following http://commons.apache.org/proper/commons-logging/guide.html#Configuring_The_Underlying_Logging_System

The attribute you mention above (org.apache.commons.logging.simplelog.defaultlog) should only be valid if the simple logger is been used. If you are running on JDK 1.4 or higher however it should default to using the JDK logging. In which case it defaults to using the lib/logging.properties from the JRE install location.

In my case I had Log4j in the classpath, so it defaulted to that.

To take away the randomness of all this you can explicitly set the Logger yourself. Create a commons-logging.properties file in the classpath and pass in the logger to use e.g.

# JDK Logging
#org.apache.commons.logging.Log=org.apache.commons.logging.impl.Jdk14Logger
# Log4j logging (also required log4j.jar to be in classpath)
org.apache.commons.logging.Log=org.apache.commons.logging.impl.Log4JLogger

For log4j, adding the following the log4j.properties stops the warnings from HtmlUnit.

log4j.logger.com.gargoylesoftware.htmlunit=ERROR

You can also use:

org.apache.log4j.Logger.getLogger("com.gargoylesoftware.htmlunit").setLevel(org.apache.log4j.Level.FATAL);
java.util.logging.Logger.getLogger("com.gargoylesoftware.htmlunit").setLevel(java.util.logging.Level.SEVERE);

Try putting this in your code:

LogManager.getLogManager().reset();