I get this error \"log4j:ERROR Failed to rename\" in my tomcat server log. I have multiple DailyRollingFileAppender in my log4j XML. And each appender points to different file.
It appears that if you're running windows this is a known bug:
see here: http://do.whileloop.org/2014/02/14/log4j-rolling-file-appenders-in-windows/
See here: https://issues.apache.org/bugzilla/show_bug.cgi?id=29726
And also here: http://www.coderanch.com/t/424837/java/java/Log-log-file-rolled-day