I am facing an issue when opening PDF files in Emacs. I always get prompted for "Selecting the encoding system (default raw-text)". The prompt comes up twice. The content of the *Warning* buffer is as follows.

These default coding systems were tried to encode text
in the buffer  *temp file*:
  (utf-8-unix (11 . 4194256) (12 . 4194260) (13 . 4194245) (14 . 4194264) (80 . 4194257) (82 .
  4194203) (86 . 4194279) (88 . 4194300) (89 . 4194200) (91 . 4194245) (92 . 4194264))
However, each of them encountered characters it couldnt encode:
  utf-8-unix cannot encode these:           ...

Click on a character (or switch to this window by C-x o
and select the characters by RET) to jump to the place it appears,
where C-u C-x = will give information about it.

Select one of the safe coding systems listed below,
or cancel the writing with C-g and edit the buffer
   to remove or modify the problematic characters,
or specify any other coding system (and risk losing
   the problematic characters).

  raw-text no-conversion

I have the following set in my init.el, so I am unsure as to what more is required.

(setq locale-coding-system 'utf-8)
(prefer-coding-system 'utf-8)
(set-default-coding-systems 'utf-8)
(set-keyboard-coding-system 'utf-8)
(set-language-environment 'utf-8)
(set-selection-coding-system 'utf-8)
(set-terminal-coding-system 'utf-8)

I also have pdf-tools set up.

(declare-function pdf-view-mode "pdf-tools")
(declare-function pdf-annot-delete "pdf-tools")
(declare-function pdf-annot-add-highlight-markup-annotation "pdf-tools")
(declare-function pdf-annot-add-text-annotation "pdf-tools")

(unless (fboundp 'pdf-view-mode)
  (autoload #'pdf-view-mode "pdf-tools" nil t))
(unless (fboundp 'isearch-forward)
  (autoload #'isearch-forward "pdf-tools" nil t))
(unless (fboundp 'pdf-annot-delete)
  (autoload #'pdf-annot-delete "pdf-tools" nil t))
(unless (fboundp 'pdf-annot-add-highlight-markup-annotation)
  (autoload #'pdf-annot-add-highlight-markup-annotation "pdf-tools" nil t))
(unless (fboundp 'pdf-annot-add-text-annotation)
  (autoload #'pdf-annot-add-text-annotation "pdf-tools" nil t))
(unless (fboundp 'pdf-tools-install)
  (autoload #'pdf-tools-install "pdf-tools" nil t))
(unless (fboundp 'pdf-loader-install)
  (autoload #'pdf-loader-install "pdf-tools" nil t))

;; Expensive to load
(run-with-idle-timer 2 nil #'require 'pdf-tools nil t)

(add-to-list 'magic-mode-alist '("%PDF" . pdf-view-mode))

(add-to-list 'auto-mode-alist '("\\.pdf\\'" . pdf-view-mode))

(with-eval-after-load 'pdf-tools
  ;; (pdf-tools-install :no-query)
  (pdf-loader-install) ; Expected to be faster than `(pdf-tools-install)'

  (defvar pdf-annot-activate-created-annotations)
  (defvar pdf-view-resize-factor)

  (setq pdf-annot-activate-created-annotations t ; Automatically annotate highlights
        ;; Fine-grained zoom factor of 10%
        pdf-view-resize-factor 1.1)

  (setq-default pdf-view-display-size 'fit-width) ; Buffer-local variable

  (add-hook 'pdf-view-mode #'pdf-links-minor-mode)
  (add-hook 'pdf-view-mode #'pdf-isearch-minor-mode)
  (add-hook 'pdf-view-mode #'pdf-outline-minor-mode)
  (add-hook 'pdf-view-mode #'pdf-history-minor-mode)

  ;; (add-hook 'pdf-view-mode-hook (lambda ()
  ;;                                 (setq header-line-format nil)))


(defvar pdf-view-mode-map)
(bind-keys :package pdf-tools :map pdf-view-mode-map
           ("C-s" . isearch-forward)
           ("d"   . pdf-annot-delete)
           ("h"   . pdf-annot-add-highlight-markup-annotation)
           ("t"   . pdf-annot-add-text-annotation))

(with-eval-after-load 'saveplace
  (with-eval-after-load 'pdf-tools
    (require 'saveplace-pdf-view nil nil)))

My GNU Emacs version is 27.1 on Ubuntu 20.04. Please suggest how can I suppress or resolve the above annoyance.

  • Does pdf-tools work otherwise? Do the same prompts/warnings also occur if you run emacs -Q and open the PDF files? Does this happen for all PDFs? (maybe grab some random examples online if all your local examples have a similar source).
    – phils
    Commented Apr 29, 2021 at 2:06
  • This happens for PDF files I have built locally with LaTeX. It does not happen with externally-built PDFs. Commented May 1, 2021 at 4:12
  • And what about the other two questions?
    – phils
    Commented May 1, 2021 at 8:07
  • pdf-tools work by itself. emacs -Q followed by package-initialize() and pdf-tools-install also work, that is, I do not see the "Select coding system". However, Emacs now works with my configuration as well, which is weird. I do not remember having made any related modifications in the last one week, so I am confused. I will follow up with more information when I have it. Thanks for helping. Commented May 3, 2021 at 6:33

2 Answers 2


You can try to find out what triggers it by doing M-x debug-on-entry select-safe-coding-system (then read until the debugger gets triggered).

For me the pop-up seems to get triggered by git-gutter-mode. Simply deactivating that mode stops the very annoying behavior.

(Subsequently, the debugger also got triggered by pdf-view-restore, but the problem was already solved by deactivating git-gutter-mode. So after 'fixing' the first trigger, first do M-x cancel-debug-on-entry before you start fixing subsequent triggers. I have no idea why those other triggers do not trigger the pop-up, but that is another mystery...)


As pointed out by dalanicolai, the problem is git-gutter in this case.

This is what my configuration looks like now:

(use-package git-gutter
  (setq git-gutter:update-interval 0.25)

  (defun rpo/git-gutter-mode ()
    "Enable git-gutter mode if current buffer's file is under version control."
    (if (and (buffer-file-name)
        (vc-backend (buffer-file-name))
            (not (cl-some (lambda (suffix) (string-suffix-p suffix (buffer-file-name)))
                        '(".pdf" ".svg" ".png"))))
        (git-gutter-mode 1))))
(add-hook 'find-file-hook #'rpo/git-gutter-mode)

(use-package git-gutter-fringe
  (set-face-attribute 'git-gutter-fr:added nil :foreground "#99cc99" :inherit 'fringe)
  (set-face-attribute 'git-gutter-fr:modified nil :foreground "#9999cc" :inherit 'fringe)
  (set-face-attribute 'git-gutter-fr:deleted nil :foreground "#cc9999" :inherit 'fringe)
  (define-fringe-bitmap 'git-gutter-fr:added [224] nil nil '(center repeated))
  (define-fringe-bitmap 'git-gutter-fr:modified [224] nil nil '(center repeated))
  (define-fringe-bitmap 'git-gutter-fr:deleted [128 192 224 240] nil nil 'bottom))

This way, git-gutter is only activated for file types which have not been blacklisted (.pdf, .svg, and .png here) before.

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