SLF4J warning or error messages and their meanings No SLF4J providers were found. This message is a warning and not an error. It is reported when no SLF4J providers could be found on the class path. SLF4J requires a logging provider because it is a logging API and not an logging implementation. Placing one (and only one) of the many available providers such as slf4j-nop.jar slf4j-simple.jar, slf4j