Lars Gustäbel <lars@gustaebel.de> added the comment: tarfile does not use the `format` argument for reading, it will be detected. You can even mix different formats in one archive and tarfile will be fine with it. ---------- nosy: +lars.gustaebel _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue30661> _______________________________________