[logback-user] breaking on startup

Robert Elliot rob at lidalia.org.uk
Wed May 13 20:14:10 CEST 2009

You have slf4j-log4j12.jar, logback-classic.jar and slf4j-simple.jar  
on your classpath - that's three separate SLF4J implementations.  You  
should have only one (logback-classic, presumably).  It's initialising  
SLF4J Simple, so when you retrieve the SLF4J LoggerFactory it's  
returning an org.slf4j.impl.SimpleLoggerFactory which you then try and  
cast to ch.qos.lobgack.LoggerFactory, which naturally fails.

Take slf4j-log4j12.jar and slf4j-simple.jar off your classpath - if  
you are trying to redirect log4j to slf4j then you need log4j-over- 
slf4j.jar, not slf4j-log4j12.jar which instead uses log4j as the slf4j  

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