The rotating file handlers use File.moveTo() which is noted in the JavaDoc as being highly implementation dependent. One example of this is that on Linux it will replace an existing target, but on Windows it will fail when doing that.

A consequence of this is that if the periodic rotating file handler re-uses a file name, e.g. with a suffix only containing the date and not month or year, it will throw an exception, and continue logging to the same file.

This can be fixed by using Files.move() with the option to replace the target file.