[logback-user] breaking on startup

Ceki Gulcu ceki at qos.ch
Wed May 13 20:23:11 CEST 2009

Right on.

Robert Elliot wrote:
> 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 implementation.

Ceki Gülcü
Logback: The reliable, generic, fast and flexible logging framework for Java.

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