Exception thrown while using logback/slf4j

Question

I am using slf4j 1.6.2 api jar (tried using 1.6.1 as well) - logback version is 0.9.29 (core & classic). I am using jdk1.6 on ubuntu. The exception I received is copied

Answer 1

It very much looks like the version of slf4j-api.jar being loaded by the JVM has version 1.5.x. You surely have slf4j-api-1.5.x.jar on your class path (in addition to slf4j-api-1.6.2.jar). Check your class path.