Folks,<div><br></div><div>I define a number of locally scoped properties in my logback configuration which are reused throughout the remainder of the file. For example:</div><div><br></div><div><div>&lt;property name=&quot;LOG_DATE_FORMAT&quot; value=&quot;&#39;yyyy-MM-dd HH:mm:ss,SSS Z&#39;&quot; /&gt;</div>

<div>&lt;property name=&quot;LOG_TIMEZONE&quot; value=&quot;&quot; /&gt;</div><div>&lt;property name=&quot;LOG_BASEDIR&quot; value=&quot;${catalina.base}/logs/myappname&quot; /&gt;</div></div><div><br></div><div>...</div>

<div>...</div><div>...</div><div><br></div><div><div>  &lt;appender name=&quot;MyAppName-RFA&quot; class=&quot;ch.qos.logback.core.rolling.RollingFileAppender&quot;&gt;</div><div>    &lt;file&gt;${LOG_BASEDIR}/myappname.log&lt;/file&gt;</div>

<div><br></div><div>    &lt;filter class=&quot;ch.qos.logback.classic.filter.ThresholdFilter&quot;&gt;</div><div>      &lt;level&gt;DEBUG&lt;/level&gt;</div><div>    &lt;/filter&gt;</div><div><br></div><div>    &lt;rollingPolicy class=&quot;ch.qos.logback.core.rolling.TimeBasedRollingPolicy&quot;&gt;</div>

<div>      &lt;!-- Monthly Rollover, 24 Month Retention --&gt;</div><div>      &lt;fileNamePattern&gt;${LOG_BASEDIR}/archive/%d{yyyy,aux}/myappname.%d{MM}.log.gz&lt;/fileNamePattern&gt;</div><div>      &lt;maxHistory&gt;24&lt;/maxHistory&gt;</div>

<div>    &lt;/rollingPolicy&gt;</div><div><br></div><div>    &lt;encoder&gt;</div><div>      &lt;pattern&gt;%d{${LOG_DATE_FORMAT},${LOG_TIMEZONE}} %-6p [%X{MyAppName-UUID}] %c:%M - %m%n&lt;/pattern&gt;</div><div>      &lt;outputPatternAsHeader&gt;false&lt;/outputPatternAsHeader&gt;</div>

<div>    &lt;/encoder&gt;</div><div>  &lt;/appender&gt;</div></div><div><br></div><div>I have multiple rolling file appenders, so rather than define the values manually for each appender, I define the local property and reuse as appropriate.</div>

<div><br></div><div>However, by default the LOG_TIMEZONE value is empty - I only want this value to be populated when a specific timezone is required. However, as a result of defining this property but specifying no value I get the following error message at startup:<br>

<br>18:30:41,402 |-ERROR in ch.qos.logback.core.joran.action.PropertyAction - In &lt;property&gt; element, either the &quot;file&quot; attribute alone, or the &quot;resource&quot; element alone, or both the &quot;name&quot; and &quot;value&quot; attributes must be set.<br>

</div><div><br></div><div>I assume from this error message that a property cannot have a NULL/empty value - i.e. this is expected behaviour? I guess I could remove/comment the property if it is not being used in the current configuration - although I&#39;d rather not remove it from the configuration file completely, since its presence also acts as a visual reminder of which properties can be set.</div>

<div><br></div><div>Regards,</div><div><br></div><div>Shane</div>