<?xml version="1.0" encoding="UTF-8"?>

<configuration monitorInterval="3">
    <appenders>
        <File name="FILE" fileName="logs/error.log"/>
    </appenders>
    <loggers>
        <root level="error">
            <appender-ref ref="FILE"/>
        </root>
    </loggers>

</configuration>

public static Logger log = LogManager.getLogger(Start.class);

public static Logger log = LogManager.getLogger(SomeClass.class);