Hello. I have this simple Python test program:  #! /usr/bin/env python3 import numpy as np x = np.array([0, 1, 2, 3]) y = np.array([0, 1, 4, 9]) def gen_segments(x, y): for i in range(0, len(x)-1): yield (x[i], x[i+1]), (y[i], y[i+1]) lines = [list(zip(s, t)) for s, t in gen_segments(x, y)] when I position the cursor at the end of the line starting with yield and press ENTER, Emacs gives me the following error: "Lisp nesting exceeds ‘max-lisp-eval-depth’" I am using Emacs version 25.2 on Ubuntu 17.04. Here is a minimal setup to reproduce the problem:  $ emacs -Q -l init.el t.py where "t.py" is the above python program, and "init.el" is:  (setq debug-on-error t) (setq package-load-list '((python-mode t))) (package-initialize) (setq package-enable-at-startup nil) The Python mode that package-initialize above loads was installed with the Emacs package manager as python-mode-20170307.457 in my elpa directory. If I comment out the line (package-initialize) above, it works fine (then Emacs uses the Python mode in /opt/emacs-25.2/share/emacs/25.2/lisp/progmodes/python.el.gz instead). Best regards, Håkon Hægland ----------- Configured using: 'configure CFLAGS=-no-pie --with-xft --prefix=/opt/emacs-25.2' Configured features: XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GCONF GSETTINGS NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 Important settings: value of $LC_MONETARY: nb_NO.UTF-8 value of $LC_NUMERIC: nb_NO.UTF-8 value of $LC_TIME: nb_NO.UTF-8 value of $LANG: en_US.UTF-8 value of $XMODIFIERS: @im=ibus locale-coding-system: utf-8-unix