SLF4J warning or error messages and their meanings No SLF4J providers were found. This warning, i.e. not an error, message is reported when no SLF4J providers could be found on the class path. Placing one (and only one) of the many available providers such as slf4j-nop.jar slf4j-simple.jar, slf4j-reload4j.jar, slf4j-jdk14.jar or logback-classic.jar on the class path should solve the problem. In th