Indeed! The tresholdFilter seems to be what I need : http://logback.qos.ch/manual/filters.html#thresholdFilter. I skipped the filter part when I was reading for general purpose information. I thought it was for very advanced user. Thanks, Bertrand Dechoux --------------------------------- Hello, You can create 2 appenders : - one for your specific file (only errors) and the other with all levels - use filters in the first one : http://logback.qos.ch/manual/filters.html the way the 1st appender log only the logs with level.isEquals error level --------------------------------- Hi, I am new to logback configuration. I have read the online manual but clearly not in depth. I would like to log in a separate file all ERROR logs but keep these logs at the same time where they are supposed to be. I understand I could use root with an ERROR level and a file appender but then I woul lose all the details (logs lower than ERROR). Is there any obvious way that I might have missed? Regards, Bertrand Dechoux