Hello, I am using slf4j with logback as backend log solution. When I trying to make the log file support Unicode, I add <encoder><charset>UTF-8</charset><encoder> to logback.xml, However I find problems. My slf4j-api version 1.7.20 Logback-classic and logback-core: 1.1.7 Code: package cbao.cmdtests; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * @author cbao * */ public class LogTests { /** * @param args * @throws InterruptedException */ public static void main(String[] args) throws InterruptedException { Logger logger = LoggerFactory.getLogger("LogTests"); for (int i = 0; i < 5000; i++) { logger.info("This is ANSI text"); Thread.sleep(0); } logger.info("This is unicode text: 中文"); } } Logback.xml: <?xml version="1.0" encoding="UTF-8"?> <configuration scan="true"> <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender"> <encoder> <charset>UTF-8</charset> <Pattern>%d %-4relative [%thread] %-5level %logger{35} - %msg%n</Pattern> </encoder> </appender> <appender name="FILE" class="ch.qos.logback.core.FileAppender"> <file>logs/application.log</file> <encoder> <charset>UTF-8</charset> <pattern>%d %-4relative [%thread] %-5level %logger{35} - %msg%n</pattern> <immediateFlush>true</immediateFlush> </encoder> </appender> <root level="DEBUG"> <appender-ref ref="consoleAppender" /> <appender-ref ref="FILE"/> </root> </configuration> After running above code, the log file format is 1252 (ANSI – Latin I) The end of log file: 2016-04-21 17:00:12,666 151328 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:12,717 151379 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:12,767 151429 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:12,817 151479 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:12,867 151529 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:12,918 151580 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:12,968 151630 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:13,019 151681 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:13,070 151732 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:13,120 151782 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:13,171 151833 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:13,222 151884 [main] INFO LogTests - This is ANSI text 2016-04-21 17:00:13,273 151935 [main] INFO LogTests - This is unicode text: 中文 As my test, if there is no unicode log, the newly created log file will be 1252 (ANSI – Latin I). As soon as first unicode string logged, the log file changed (unicode: UTF-8). However, if there are significant ansi text before first unicode text could be logged, the log file will stay as ANSI even after utf-8 logged, then the unicode log can’t be display correctly. Is there any switches in logback.xml can fix it? Thanks Cheng Bao