Using mixed versions of slf4j causes SLF4J to print to console a WARN about this -------------------------------------------------------------------------------- Key: FORGE-2531 URL: https://issues.jboss.org/browse/FORGE-2531 Project: Forge Issue Type: Bug Affects Versions: 2.20.1.Final Reporter: Claus Ibsen Priority: Minor Fix For: 3.x Future You can reproduce by installing the fabric8 devops addon {code} addon-install --coordinate io.fabric8.forge:devops,2.2.63 ***SUCCESS*** Addon io.fabric8.forge:devops,2.2.63 was installed successfully. [forge-distribution-2.20.1.Final]$ deSLF4J: Class path contains multiple SLF4J bindings. SLF4J: Found binding in [jar:file:/opt/forge-distribution-2.20.1.Final/addons/org-jboss-forge-addon-maven-2-20-1-Final/slf4j-jdk14-1.7.5.jar!/org/slf4j/impl/StaticLoggerBinder.class] SLF4J: Found binding in [jar:file:/opt/forge-distribution-2.20.1.Final/addons/org-jboss-forge-addon-database-tools-2-20-1-Final/slf4j-jdk14-1.5.8.jar!/org/slf4j/impl/StaticLoggerBinder.class] SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation. SLF4J: Actual binding is of type [org.slf4j.impl.JDK14LoggerFactory] {code} And then wait some seconds then you see all the slf4j logging. As you can see those 2 addons from forge itself are using mixed slf4j versions. 1.7.5 and 1.5.8