Hello, I have caught a problem of using embedded Jetty and slf4j, may be you can help me. Jetty tell me this one: java.lang.LinkageError: loader constraint violation: when resolving method "org.slf4j.impl.StaticLoggerBinder.getLoggerFactory()Lorg/slf4j/ILoggerFactory;" the class loader (instance of org/eclipse/jetty/webapp/WebAppClassLoader) of the current class, org/slf4j/LoggerFactory, and the class loader (instance of sun/misc /Launcher$AppClassLoader) for resolved class, org/slf4j/impl/StaticLoggerBinder, have different Class objects for the type org/slf4j/ILoggerFactory used in the signature [main o.e.j.u.l.Slf4jLog.warn:111] I have next jars: Embedded Jetty classpath: slf4j-api-1.5.10.jar logback-classic-0.9.18.jar War libs: slf4j-api-1.5.10.jar But I add slf4j-api-1.5.10.jar logback-classic-0.9.18.jar to WAR libs and delete logback-classic-0.9.18.jar from jetty classpath, all work fine. Best regards, Aleksey Didik