I've got problems with image-mode triggered by scad-preview, but I have tiny code example to trigger it: (pop-to-buffer (with-current-buffer (get-buffer-create "mybuf") (insert-file-contents "~/pics/nav1.jpg") (major-mode-suspend) (setq major-mode 'image-mode) (image-toggle-display-image) (current-buffer))) ===> Debugger entered--Lisp error: (wrong-type-argument stringp nil) file-name-nondirectory(nil) file-name-extension(nil) image--imagemagick-wanted-p(nil) (if (image--imagemagick-wanted-p filename) 'imagemagick (image-type file-or-data nil data-p)) (let* ((filename (buffer-file-name)) (data-p (not (and filename (file-readable-p filename) (not (file-remote-p filename)) (not (buffer-modified-p)) (not (and (boundp ...) archive-superior-buffer)) (not (and (boundp ...) tar-superior-buffer)) (not (and (boundp ...) (local-variable-p ...)))))) (file-or-data (if data-p (let ((str (buffer-substring-no-properties ... ...))) (if enable-multibyte-characters (encode-coding-string str buffer-file-coding-system) str)) filename)) (edges (and (null image-transform-resize) (window-inside-pixel-edges (get-buffer-window (current-buffer))))) (type (if (image--imagemagick-wanted-p filename) 'imagemagick (image-type file-or-data nil data-p))) (image (if (not edges) (create-image file-or-data type data-p) (create-image file-or-data type data-p :max-width (- (nth 2 edges) (nth 0 edges)) :max-height (- (nth 3 edges) (nth 1 edges))))) (inhibit-read-only t) (buffer-undo-list t) (modified (buffer-modified-p)) props) (image-flush image) (setq image (append image (image-transform-properties image))) (setq props (cons 'display (cons image '(rear-nonsticky (display) read-only t front-sticky (read-only))))) (let ((create-lockfiles nil)) (add-text-properties (point-min) (point-max) props) (restore-buffer-modified-p modified)) (setq cursor-type nil) (setq truncate-lines t) (if (coding-system-equal (coding-system-base buffer-file-coding-system) 'no-conversion) (set (make-local-variable 'find-file-literally) t)) (set (make-local-variable 'auto-hscroll-mode) nil) (setq image-type type) (if (eq major-mode 'image-mode) (setq mode-name (format "Image[%s]" type))) (image-transform-check-size) (if (called-interactively-p 'any) (message "Repeat this command to go back to displaying the file as text"))) image-toggle-display-image() (save-current-buffer (set-buffer (get-buffer-create "mybuf")) (insert-file-contents "~/pics/nav1.jpg") (major-mode-suspend) (setq major-mode 'image-mode) (image-toggle-display-image) (current-buffer)) (pop-to-buffer (save-current-buffer (set-buffer (get-buffer-create "mybuf")) (insert-file-contents "~/pics/nav1.jpg") (major-mode-suspend) (setq major-mode 'image-mode) (image-toggle-display-image) (current-buffer))) eval((pop-to-buffer (save-current-buffer (set-buffer (get-buffer-create "mybuf")) (insert-file-contents "~/pics/nav1.jpg") (major-mode-suspend) (setq major-mode 'image-mode) (image-toggle-display-image) (current-buffer))) nil) elisp--eval-last-sexp(nil) eval-last-sexp(nil) funcall-interactively(eval-last-sexp nil) call-interactively(eval-last-sexp nil nil) command-execute(eval-last-sexp) This can be fixed by this tiny patch: diff --git a/lisp/image-mode.el b/lisp/image-mode.el index 606c661..49354a6 100644 --- a/lisp/image-mode.el +++ b/lisp/image-mode.el @@ -738,7 +738,7 @@ image-toggle-display-image (edges (and (null image-transform-resize) (window-inside-pixel-edges (get-buffer-window (current-buffer))))) - (type (if (image--imagemagick-wanted-p filename) + (type (if (and filename (image--imagemagick-wanted-p filename)) 'imagemagick (image-type file-or-data nil data-p))) (image (if (not edges) Thanks In GNU Emacs 27.0.50 (build 5, x86_64-pc-linux-gnu, GTK+ Version 3.18.9) of 2018-07-14 built on wrt Repository revision: 155d7303808345dd73427302d9a352ec5461c11a Windowing system distributor 'The X.Org Foundation', version 11.0.11804000 System Description: Ubuntu 16.04.1 LTS Recent messages: Entering debugger... Back to top level funcall-interactively: Buffer is read-only: # [4 times] Quit Read-Only mode disabled in current buffer image-toggle-display-image Saving file /usr/local/share/emacs/27.0.50/lisp/image-mode.el.gz... Quit # Mark set next-line: End of buffer Configured using: 'configure --with-xwidgets --with-modules' Configured features: XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GSETTINGS NOTIFY GNUTLS LIBXML2 FREETYPE XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 MODULES THREADS XWIDGETS JSON LCMS2 Important settings: value of $LC_MONETARY: ru_RU.UTF-8 value of $LC_NUMERIC: ru_RU.UTF-8 value of $LC_TIME: ru_RU.UTF-8 value of $LANG: en_US.UTF-8 locale-coding-system: utf-8-unix Major mode: Lisp Interaction Minor modes in effect: icomplete-mode: t save-place-mode: t diff-auto-refine-mode: t pyvenv-mode: t shell-dirtrack-mode: t display-time-mode: t global-undo-tree-mode: t undo-tree-mode: t cl-old-struct-compat-mode: t global-eldoc-mode: t eldoc-mode: t mouse-wheel-mode: t file-name-shadow-mode: t global-font-lock-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t column-number-mode: t line-number-mode: t auto-fill-function: do-auto-fill transient-mark-mode: t Load-path shadows: /home/lg/.emacs.d/elpa/flim-20180328.1624/hex-util hides /usr/local/share/emacs/27.0.50/lisp/hex-util /home/lg/.emacs.d/elpa/flim-20180328.1624/md4 hides /usr/local/share/emacs/27.0.50/lisp/md4 /home/lg/.emacs.d/elpa/flim-20180328.1624/sasl hides /usr/local/share/emacs/27.0.50/lisp/net/sasl /home/lg/.emacs.d/elpa/flim-20180328.1624/sasl-digest hides /usr/local/share/emacs/27.0.50/lisp/net/sasl-digest /home/lg/.emacs.d/elpa/flim-20180328.1624/hmac-md5 hides /usr/local/share/emacs/27.0.50/lisp/net/hmac-md5 /home/lg/.emacs.d/elpa/flim-20180328.1624/ntlm hides /usr/local/share/emacs/27.0.50/lisp/net/ntlm /home/lg/.emacs.d/elpa/flim-20180328.1624/hmac-def hides /usr/local/share/emacs/27.0.50/lisp/net/hmac-def /home/lg/.emacs.d/elpa/flim-20180328.1624/sasl-ntlm hides /usr/local/share/emacs/27.0.50/lisp/net/sasl-ntlm /home/lg/.emacs.d/elpa/flim-20180328.1624/sasl-cram hides /usr/local/share/emacs/27.0.50/lisp/net/sasl-cram Features: (shadow sort mail-extr emacsbug sendmail jka-compr image-mode find-func dabbrev skeleton cl-print debug misearch multi-isearch vc-git exwm-wconf winner exwm-misc exwm exwm-match exwm-input xcb-keysyms exwm-manage exwm-floating xcb-cursor xcb-render exwm-layout exwm-workspace exwm-core xcb-ewmh xcb-icccm xcb xcb-xproto xcb-types work desktop frameset gnus-demon nntp gnus-group gnus-undo gnus-start gnus-cloud nnimap nnmail mail-source utf7 netrc gnus-spec gnus-win nnoo gnus-int gnus-range message rmc puny dired dired-loaddefs rfc822 mml mml-sec epa mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader gnus nnheader gnus-util rmail rmail-loaddefs rfc2047 rfc2045 ietf-drums mail-utils mm-util mail-prsvr autoinsert cal-menu calendar cal-loaddefs icomplete saveplace cython-mode help-fns radix-tree elpy find-file-in-project ivy delsel ivy-overlay ffap windmove diff-mode easy-mmode elpy-shell pyvenv elpy-profile elpy-django elpy-refactor python tramp-sh tramp trampver tramp-compat tramp-loaddefs ucs-normalize parse-time format-spec grep files-x etags xref project cus-edit cus-start cus-load wid-edit python-mode info-look which-func imenu shell pcomplete hippie-exp flymake-proc flymake warnings thingatpt compile cc-cmds cc-engine cc-vars cc-defs dot-mode server time elec-pair google-translate google-translate-default-ui google-translate-core-ui google-translate-core google-translate-tk url url-proxy url-privacy url-expand url-methods url-history url-cookie url-domsuf url-util mailcap whitespace undo-tree diff ido comint ansi-color ring avoid edmacro kmacro browse-kill-ring advice cl time-date mule-util gh-common gh-profile rx s marshal eieio-compat dash info finder-inf package let-alist derived pcase cl-extra help-mode easymenu url-handlers url-parse auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs password-cache json map url-vars seq byte-opt gv bytecomp byte-compile cconv epg epg-config subr-x cl-loaddefs cl-lib tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode lisp-mode prog-mode register page menu-bar rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock syntax facemenu font-core term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european ethiopic indian cyrillic chinese composite charscript charprop case-table epa-hook jka-cmpr-hook help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs button faces cus-face macroexp files text-properties overlay sha1 md5 base64 format env code-pages mule custom widget hashtable-print-readable backquote threads dbusbind inotify lcms2 dynamic-setting system-font-setting font-render-setting xwidget-internal move-toolbar gtk x-toolkit x multi-tty make-network-process emacs) Memory information: ((conses 16 563189 81695) (symbols 48 47128 2) (miscs 40 153 288) (strings 32 109019 4813) (string-bytes 1 16393106) (vectors 16 69322) (vector-slots 8 1268890 24336) (floats 8 270 396) (intervals 56 1507 1235) (buffers 992 24) (heap 1024 71980 33557)) -- lg