2016-11-03 16:43:56,508 ajp-172.18.8.1-8009-2 ERROR An exception occurred processing Appender FILE java.lang.NullPointerException
        at org.apache.logging.log4j.core.impl.ThrowableProxy.loadClass(ThrowableProxy.java:559)
        at org.apache.logging.log4j.core.impl.ThrowableProxy.loadClass(ThrowableProxy.java:550)
        at org.apache.logging.log4j.core.impl.ThrowableProxy.toExtendedStackTrace(ThrowableProxy.java:660)
        at org.apache.logging.log4j.core.impl.ThrowableProxy.<init>(ThrowableProxy.java:137)
        at org.apache.logging.log4j.core.impl.ThrowableProxy.<init>(ThrowableProxy.java:121)
        at org.apache.logging.log4j.core.impl.MutableLogEvent.getThrownProxy(MutableLogEvent.java:329)
        at org.apache.logging.log4j.core.pattern.ExtendedThrowablePatternConverter.format(ExtendedThrowablePatternConverter.java:61)
        at org.apache.logging.log4j.core.pattern.PatternFormatter.format(PatternFormatter.java:38)
        at org.apache.logging.log4j.core.layout.PatternLayout$PatternSerializer.toSerializable(PatternLayout.java:294)
        at org.apache.logging.log4j.core.layout.PatternLayout.toText(PatternLayout.java:195)
        at org.apache.logging.log4j.core.layout.PatternLayout.encode(PatternLayout.java:180)
        at org.apache.logging.log4j.core.layout.PatternLayout.encode(PatternLayout.java:57)
        at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.directEncodeEvent(AbstractOutputStreamAppender.java:176)
        at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.tryAppend(AbstractOutputStreamAppender.java:169)
        at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.append(AbstractOutputStreamAppender.java:160)
        at org.apache.logging.log4j.core.appender.RollingFileAppender.append(RollingFileAppender.java:281)
        at org.apache.logging.log4j.core.config.AppenderControl.tryCallAppender(AppenderControl.java:156)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppender0(AppenderControl.java:129)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppenderPreventRecursion(AppenderControl.java:120)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:84)
        at org.apache.logging.log4j.core.config.LoggerConfig.callAppenders(LoggerConfig.java:447)
        at org.apache.logging.log4j.core.config.LoggerConfig.processLogEvent(LoggerConfig.java:432)
        at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:416)
        at org.apache.logging.log4j.core.config.LoggerConfig.logParent(LoggerConfig.java:438)
        at org.apache.logging.log4j.core.config.LoggerConfig.processLogEvent(LoggerConfig.java:433)
        at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:416)
        at org.apache.logging.log4j.core.config.LoggerConfig.logParent(LoggerConfig.java:438)
        at org.apache.logging.log4j.core.config.LoggerConfig.processLogEvent(LoggerConfig.java:433)
        at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:416)
        at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:402)
        at org.apache.logging.log4j.core.config.AwaitCompletionReliabilityStrategy.log(AwaitCompletionReliabilityStrategy.java:63)
        at org.apache.logging.log4j.core.Logger.logMessage(Logger.java:146)
        at org.apache.logging.log4j.spi.AbstractLogger.logMessageSafely(AbstractLogger.java:2091)
        at org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:1988)
        at org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:1960)
        at org.apache.logging.slf4j.Log4jLogger.error(Log4jLogger.java:319)
        ....