# How to replace log4j with logback **URL:** \ **Category:** Elasticsearch\ **Created:** [March 22, 2017, 7:39am UTC](https://discuss.elastic.co/t/how-to-replace-log4j-with-logback/79544 "2017-03-22T07:39:16Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![iGetIT](https://avatars.discourse-cdn.com/v4/letter/i/278dde/32.png) [@iGetIT](https://discuss.elastic.co/u/iGetIT)\ **Post date:** [March 22, 2017, 7:39am UTC](https://discuss.elastic.co/t/how-to-replace-log4j-with-logback/79544/1 "2017-03-22T07:39:16Z")
I'd like logback ! But I failed in my first time to test elasticsearch ! ```auto org.slf4j slf4j-api 1.7.21 ch.qos.logback logback-classic 1.1.7 ch.qos.logback logback-core 1.1.7 org.elasticsearch.client transport 5.1.2 ``` It printed error messages on console ```auto java.lang.NoClassDefFoundError: org/apache/logging/log4j/Logger at org.elasticsearch.common.logging.Loggers.getLogger(Loggers.java:105) at org.elasticsearch.common.logging.Loggers.getLogger(Loggers.java:72) at org.elasticsearch.common.component.AbstractComponent.(AbstractComponent.java:37) at org.elasticsearch.plugins.PluginsService.(PluginsService.java:98) at org.elasticsearch.client.transport.TransportClient.newPluginService(TransportClient.java:94) at org.elasticsearch.client.transport.TransportClient.buildTemplate(TransportClient.java:119) at org.elasticsearch.client.transport.TransportClient.(TransportClient.java:247) at org.elasticsearch.transport.client.PreBuiltTransportClient.(PreBuiltTransportClient.java:125) at org.elasticsearch.transport.client.PreBuiltTransportClient.(PreBuiltTransportClient.java:111) at org.elasticsearch.transport.client.PreBuiltTransportClient.(PreBuiltTransportClient.java:101) at com.template.test.util.elastic.EsClientUtil.(EsClientUtil.java:45) at com.template.test.util.elastic.EsClientUtilTest.setUp(EsClientUtilTest.java:20) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:24) at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68) at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51) at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:237) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147) Caused by: java.lang.ClassNotFoundException: org.apache.logging.log4j.Logger at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ... 40 more java.lang.NoClassDefFoundError: Could not initialize class com.template.test.util.elastic.EsClientUtil at com.template.test.util.elastic.EsClientUtilTest.tearDown(EsClientUtilTest.java:25) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:33) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68) at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51) at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:237) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147) ``` something was wrong , but I don't know why ! **I just want to replace log4j with logback**! help... ---
**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\ **Post date:** [March 22, 2017, 8:38am UTC](https://discuss.elastic.co/t/how-to-replace-log4j-with-logback/79544/2 "2017-03-22T08:38:25Z")
Did you read [https://www.elastic.co/guide/en/elasticsearch/client/java-api/current/\_using\_another\_logger.html](https://www.elastic.co/guide/en/elasticsearch/client/java-api/current/_using_another_logger.html) ? ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [April 19, 2017, 8:38am UTC](https://discuss.elastic.co/t/how-to-replace-log4j-with-logback/79544/3 "2017-04-19T08:38:42Z")
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