Java stack trace not printing with log4j2

Question

I am sure this is a simple fix but can't for the life of me figure out why. I am getting random NPEs and have log4j (2.0.2) logging the error, however despite having the %ex in my log4j configuration file, it prints no stack trace.

11-01-2019 02:39:33.212 [Thread-307] ERROR AlarmParse.ProcessAlarm: java.lang.NullPointerException -

Log4j2 configuration file:

<?xml version="1.0" encoding="UTF-8"?>
<configuration monitorInterval="30" status="INFO">
  <appenders>
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg - %ex%n"/>
    </Console>

    <File name="MyFile" fileName="G:/iMCAlarmParse/logs/AppLog.log">
        <PatternLayout pattern="%d{MM-dd-yyyy HH:mm:ss.SSS} [%t] %-5level %c{2}: %msg - %ex%n"/>
    </File>

Java:

try {
    //<Many sequential class calls>
} catch (Exception e) {
    log4j.error(e);
}

sazzad · Accepted Answer · 2019-11-04 04:53:05Z

7

By log4j.error(e) you are actually invoking info(Object message) method which does not take extra care of Exception.

But, to print stack trace, you need to invoke one of the variants which handles Throwable (super class of Exception) separately. One of the easiest method for this could be info(CharSequence arg0, Throwable arg1).

E.g. you can simply change the line in the catch block to:

log4j.error("", e);

answered Nov 4, 2019 at 4:53

sazzad

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3 Comments

Beeker Over a year ago

Awesome. I've recompiled and am deploying the JAR to the server. Now we wait.... :)

Beeker Over a year ago

Perfect, thanks. The stack trace seems a bit short, but it identified the failing class.

sazzad Over a year ago

Try %ex{full} for stack trace.

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