This bug report will be sent to the Bug-GNU-Emacs mailing list and the GNU bug tracker at debbugs.gnu.org. Please check that the From: line contains a valid email address. After a delay of up to one day, you should receive an acknowledgment at that address. Please write in English if possible, as the Emacs maintainers usually do not have translators for other languages. Please describe exactly what actions triggered the bug, and the precise symptoms of the bug. If you can, give a recipe starting from `emacs -Q': When I save a python file with an incomplete function definition, i.e. file containing the following lines: 1 def f(): 2 3 def g(): 4 return null and then move my cursos to line 2 and press TAB, I get "Arithmetic Error" which is fixed by M-x set-variable RET python-indent-offset RET 4 RET. This suggests that the auto-detection of the indentation offset is not working properly. Thanks, Contact me at vadim.kulikov@iki.fi, if needed. If Emacs crashed, and you have the Emacs process in the gdb debugger, please include the output from the following gdb commands: `bt full' and `xbacktrace'. For information about debugging Emacs, please read the file /usr/share/emacs/24.3/etc/DEBUG. In GNU Emacs 24.3.1 (x86_64-pc-linux-gnu, GTK+ Version 3.10.7) of 2014-03-07 on lamiak, modified by Debian System Description: Ubuntu 14.04.5 LTS Configured using: `configure '--build' 'x86_64-linux-gnu' '--build' 'x86_64-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' '--localstatedir=/var/lib' '--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes' '--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.3/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.3/site-lisp:/usr/share/emacs/site-lisp' '--with-crt-dir=/usr/lib/x86_64-linux-gnu' '--with-x=yes' '--with-x-toolkit=gtk3' '--with-toolkit-scroll-bars' 'build_alias=x86_64-linux-gnu' 'CFLAGS=-g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wall' 'LDFLAGS=-Wl,-Bsymbolic-functions -Wl,-z,relro' 'CPPFLAGS=-D_FORTIFY_SOURCE=2'' Important settings: value of $LC_CTYPE: fi_FI.UTF-8 value of $LC_MONETARY: de_AT.UTF-8 value of $LC_NUMERIC: de_AT.UTF-8 value of $LC_TIME: de_AT.UTF-8 value of $LANG: en_GB.UTF-8 value of $XMODIFIERS: @im=ibus locale-coding-system: utf-8-unix default enable-multibyte-characters: t Major mode: Python Minor modes in effect: show-paren-mode: t tooltip-mode: t mouse-wheel-mode: t tool-bar-mode: t menu-bar-mode: t file-name-shadow-mode: t global-font-lock-mode: t font-lock-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t column-number-mode: t line-number-mode: t transient-mark-mode: t Recent input: ESC [ > 1 ; 2 8 0 2 ; 0 c ESC O B ESC O B ESC O B ESC O B ESC O B ESC O B TAB ESC x r e p o TAB r t - e m TAB RET Recent messages: Loading /etc/emacs/site-start.d/50latex-cjk-common.el (source)...done Loading /etc/emacs/site-start.d/50latex-cjk-thai.el (source)...done Loading /etc/emacs/site-start.d/50lilypond-data.el (source)...done Loading /etc/emacs/site-start.d/50python-docutils.el (source)...done Loading /etc/emacs/site-start.d/90iso-transl.el (source)... Loading iso-transl...done Loading /etc/emacs/site-start.d/90iso-transl.el (source)...done For information about GNU Emacs and the GNU system, type C-h C-a. python-indent-line: Arithmetic error Making completion list... 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