SLF4J error: This version of SLF4J requires log4j version 1.2.12 or later

When I am trying to deploy the application on Websphere 7.0 I get the error message on console

0000000d SystemErr R SLF4J: This version of SLF4J requires log4j version 1.2.12 or later. See also http://www.slf4j.org/codes.html#log4j_version

Further when spring internally calling log4j api, following error occurs:

0000000d webapp E com.ibm.ws.webcontainer.webapp.WebApp notifyServletContextCreated SRVE0283E: Exception caught while initializing context: {0} org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processEngine' defined in ServletContext resource

[/WEB-INF/spring_config/jbpm_applicationContext.xml]: Instantiation of bean failed;

nested exception is org.springframework.beans.factory.BeanDefinitionStoreException: Factory method [public org.jbpm.api.ProcessEngine org.jbpm.pvm.internal.processengine.SpringHelper.createProcessEngine()] threw exception; nested exception is java.lang.NoSuchMethodError: org/apache/log4j/Logger.trace(Ljava/lang/Object;)V

I upgraded the log4j api from 1.2.16 to 1.2.17 but still i got the same error. Additionally, slf4j-api-1.6.1.jar and slf4j-log4j12-1.6.1.jar are being used in classpath.

Solution

You should switch classloading policy for your application to "parent last". Then the version of log4j bundled with your application will be used. Please see Class loader settings for details.