Check under the external dependencies/libraries in your project in whatever ide you are using, for the slf4j dependency/library and see where its coming under,apart from the actual sl4j dependency ,under the external dependencies/libraries,if it appears in more than one place ,one of the dependencies needs to be removed ,so if you want to use slf4j logging statements ,you can try using the slf4j from the other dependency/library not from original slf4j dependency/library