Problem using log4j with axis2

Question

I created a webservice on axis2 and I used log4j for logging purposes. I'm getting the following error any time a request comes in for this WS:

log4j:ERROR A "org.apache.log4j.ConsoleAppender" object is not assignable to a "org.apache.log4j.Appender" variable.
log4j:ERROR The class "org.apache.log4j.Appender" was loaded by 
log4j:ERROR [org.apache.catalina.loader.StandardClassLoader@7f342545] whereas object of type 
log4j:ERROR "org.apache.log4j.ConsoleAppender" was loaded by [WebappClassLoader
  delegate: false
  repositories:
    /WEB-INF/classes/
----------> Parent Classloader:
org.apache.catalina.loader.StandardClassLoader@7f342545
].
log4j:ERROR Could not instantiate appender named "CONSOLE".
[ERROR] java.lang.NullPointerException

My log4j.properties is as follows:

log4j.rootCategory=INFO, CONSOLE
#log4j.rootCategory=INFO, CONSOLE, LOGFILE

# Set the enterprise logger priority to FATAL
log4j.logger.org.apache.axis2.enterprise=FATAL
log4j.logger.de.hunsicker.jalopy.io=FATAL
log4j.logger.httpclient.wire.header=FATAL
log4j.logger.org.apache.commons.httpclient=FATAL

# CONSOLE is set to be a ConsoleAppender using a PatternLayout.
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=[%p] %m%n

# LOGFILE is set to be a File appender using a PatternLayout.
log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.LOGFILE.File=axis2.log
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.LOGFILE.layout.ConversionPattern=%d [%t] %-5p %c %x - %m%n

and I have no other copies of log4j.properties anywhere in my aar.

Does anybody have any clue why I'm getting this initialization error?

Thanks in advance, PJ

Solution

You are in Jar Hell. I suspect the problem is you have 2 or more versions of the log4j jar being loaded by two different classloaders. Once I had a similar problem, though it was a different error message. I did a scan and found 7 vevrsions of log4j on my machine. Yikes!

How to avoid it? Eliminate all but one of them.

It worked for me.