Hi,
I tried setting a countdown timer in an Org buffer today for my first
time ever, but it failed with an error saying that Emacs expected a
string, but got nil.
Here is what I do:
1. Press C-x test RET to create a new buffer named 'test'.
2. Press M-x org-mode to run org-mode.
3. Press C-c C-x ; to start a countdown timer, and in the prompt that
appears, enter 1
Here is where the error occurs.
My bug report information is below, and the backtrace is attached.
Thanks!
----------------------------------------
Emacs  : GNU Emacs 25.1.1 (x86_64-apple-darwin15.6.0, NS appkit-1404.47 Version 10.11.6 (Build 15G1108))
 of 2016-11-25
Package: Org-mode version 8.2.10 (release_8.2.10 @ /usr/local/Cellar/emacs/25.1/share/emacs/25.1/lisp/org/)

current state:
==============
(setq
 org-tab-first-hook '(org-hide-block-toggle-maybe
		      org-src-native-tab-command-maybe
		      org-babel-hide-result-toggle-maybe
		      org-babel-header-arg-expand)
 outline-minor-mode-hook '(emacspeak-outline-setup-keys)
 org-speed-command-hook '(org-speed-command-default-hook
			  org-babel-speed-command-hook)
 org-occur-hook '(org-first-headline-recenter)
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-confirm-shell-link-function 'yes-or-no-p
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-src-mode-hook '(org-src-babel-configure-edit-buffer
		     org-src-mode-configure-edit-buffer)
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-babel-pre-tangle-hook '(save-buffer)
 org-mode-hook '((lambda nil
		  (org-add-hook (quote change-major-mode-hook)
		   (quote org-show-block-all) (quote append) (quote local))
		  )
		 (lambda nil
		  (org-add-hook (quote change-major-mode-hook)
		   (quote org-babel-show-result-all) (quote append)
		   (quote local))
		  )
		 emacspeak-org-mode-setup emacspeak-org-update-keys
		 #[nil "\300\301\302\303\304$\207"
		   [org-add-hook change-major-mode-hook org-show-block-all
		    append local]
		   5]
		 #[nil "\300\301\302\303\304$\207"
		   [org-add-hook change-major-mode-hook
		    org-babel-show-result-all append local]
		   5]
		 org-babel-result-hide-spec org-babel-hide-all-hashes)
 org-ctrl-c-ctrl-c-hook '(org-babel-hash-at-point
			  org-babel-execute-safely-maybe)
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers
		  org-cycle-hide-inline-tasks org-cycle-show-empty-lines
		  org-optimize-window-after-visibility-change)
 org-load-hook '(#[0 "\301B\211\207"
		   [org-store-link-functions org-eww-store-link] 2]
		 )
 org-confirm-elisp-link-function 'yes-or-no-p
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 outline-mode-hook '(emacspeak-outline-setup-keys)
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 )