The filenames generated by logging.RotatingFileHandler breaks the ability to associate a program (e.g. notepad++, sublime text, etc.) with the log files using Windows or OSX file associations because the extension is overridden by the added suffix. For example, if I specify the filename as "test.log" for a TimeBasedRotatingFileHandler with a suffix of "%Y%m%d", rolled over files are named test.log.YYYYMMDD. There is no way to associate a program with this type of file extension. A good non-breaking fix would be to add a parameter "extension" to RotatingFileHandler, and if specified would be applied to all filenames. Thus if I specify filename="test" and "extension="log" for my handler it would give "test.log" for the initial file and "test.YYYYMMDD.log" for rollover files.