I'm running an application in Tomcat 8 which uses log4j2. Everything works, but whenever I try to log something, the following message appears in Tomcat's stderr:
ERROR Unable to create Lookup for web java.lang.ClassCastException: class org.apache.logging.log4j.web.WebLookup
at java.lang.Class.asSubclass(Class.java:3396)
at org.apache.logging.log4j.core.lookup.Interpolator.<init>(Interpolator.java:64)
at org.apache.logging.log4j.core.config.PropertiesPlugin.configureSubstitutor(PropertiesPlugin.java:57)
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:483)
at org.apache.logging.log4j.core.config.plugins.util.PluginBuilder.build(PluginBuilder.java:135)
at org.apache.logging.log4j.core.config.AbstractConfiguration.createPluginObject(AbstractConfiguration.java:766)
at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:706)
at org.apache.logging.log4j.core.config.AbstractConfiguration.doConfigure(AbstractConfiguration.java:339)
at org.apache.logging.log4j.core.config.AbstractConfiguration.start(AbstractConfiguration.java:161)
at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:359)
....
what's that all about?
As I said, everything works perfectly, but I would prefer not seeing this message, as it looks like something has gone wrong.
You are probably missing the log4j-web dependency
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-web</artifactId>
<version>2.16.0</version>
</dependency>