Hello, I do have a "funny" problem - so far my understanding ... I have successfully configured LogBack and SLF4J with an DBAppender I have clients which do their logging via SocketAppender to a LogServer, which is intended to write the messages to the database. Everything (except Exceptions and MDC - see former posts) works fine, but when I added C3P0 Connection Pooling to the appender, like shown in the documentation and the examples, I do get the following StackTrace: java.lang.ExceptionInInitializerError at com.mchange.v2.naming.JavaBeanReferenceMaker.<clinit>(JavaBeanReferenceMaker.java:39) at com.mchange.v2.c3p0.impl.PoolBackedDataSourceBase.<clinit>(PoolBackedDataSourceBase.java:203) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) at java.lang.reflect.Constructor.newInstance(Unknown Source) at java.lang.Class.newInstance0(Unknown Source) at java.lang.Class.newInstance(Unknown Source) at ch.qos.logback.core.joran.action.NestedComponentIA.begin(NestedComponentIA.java:107) at ch.qos.logback.core.joran.spi.Interpreter.callBeginAction(Interpreter.java:259) at ch.qos.logback.core.joran.spi.Interpreter.startElement(Interpreter.java:126) at ch.qos.logback.core.joran.spi.Interpreter.startElement(Interpreter.java:110) at ch.qos.logback.core.joran.spi.EventPlayer.play(EventPlayer.java:36) at ch.qos.logback.core.joran.spi.Interpreter.play(Interpreter.java:336) at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:96) at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:74) at ch.qos.logback.core.joran.GenericConfigurator.doConfigure(GenericConfigurator.java:38) at ch.qos.logback.classic.util.ContextInitializer.configureByResource(ContextInitializer.java:24) at ch.qos.logback.classic.util.ContextInitializer.autoConfig(ContextInitializer.java:35) at ch.qos.logback.classic.util.ContextInitializer.autoConfig(ContextInitializer.java:46) at org.slf4j.impl.StaticLoggerBinder.initialize(StaticLoggerBinder.java:52) at org.slf4j.impl.StaticLoggerBinder.<init>(StaticLoggerBinder.java:44) at org.slf4j.impl.StaticLoggerBinder.<clinit>(StaticLoggerBinder.java:39) at org.slf4j.LoggerFactory.<clinit>(LoggerFactory.java:57) at com.mobilkom.cusi.logging.LoggingServer.<clinit>(LoggingServer.java:13) Caused by: java.lang.IllegalStateException: Logging factory implementation cannot be null. See also http://www.slf4j.org/codes.html#null_LF at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:75) at org.apache.log4j.Category.<init>(Category.java:52) at org.apache.log4j.Logger.<init>(Logger.java:22) at org.apache.log4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:38) at org.apache.log4j.Category.getLogger(Category.java:56) at org.apache.log4j.Category.getLogger(Category.java:60) at com.mchange.v2.log.log4j.Log4jMLog.getMLogger(Log4jMLog.java:51) at com.mchange.v2.log.MLog.getLogger(MLog.java:145) at com.mchange.v2.log.MLog.<clinit>(MLog.java:72) For me, it looks like, while Configuring the LogServer, the Systems tries to instantiate the DBAppender, which itself tries to setup the connection-pool which has some logging statements inside it's C3P0-CodeBase. The LoggingSystem is yet not properly initialized (Logging factory implementation cannot be null. See also http://www.slf4j.org/codes.html#null_LF) looks like "the cat is chasing it's tail" ... any ideas, hints, explanations, etc. - greatly welcome kind regards Klaus :)