I set `debug-on-error` to `t` and went through creating a log entry:
Debugger entered--Lisp error: (error "Before first headline at position 1151 in buffer
test3.org")
signal(error ("Before first headline at position 1151 in buffer
test3.org"))
error("Before first headline at position %d in buffer %s" 1151 #<buffer
test3.org>)
org-back-to-heading(t)
org-end-of-meta-data(nil)
org-log-beginning(t)
org-store-log-note()
org-ctrl-c-ctrl-c(nil)
funcall-interactively(org-ctrl-c-ctrl-c nil)
#<subr call-interactively>(org-ctrl-c-ctrl-c nil nil)
ad-Advice-call-interactively(#<subr call-interactively> org-ctrl-c-ctrl-c nil nil)
apply(ad-Advice-call-interactively #<subr call-interactively> (org-ctrl-c-ctrl-c nil nil))
call-interactively(org-ctrl-c-ctrl-c nil nil)
command-execute(org-ctrl-c-ctrl-c)
Here's ECM, which only contains all my (kudgy, inefficient, wrong?) header stuff:
#+TITLE: \zwnj^{147}Pm
#+AUTHOR: 147Pm
#+DATE: 2017-02-08T14:26:12
#+Filetags: :CompleteReWrite:
#+LANGUAGE: en
#+HTML_HEAD: <link rel="stylesheet" href="" type="text/css">
#+EXPORT_SELECT_TAGS: export
#+EXPORT_EXCLUDE_TAGS: noexport
#+OPTIONS: H:15 num:15 toc:nil \n:nil @:t ::t |:t _:{} *:t ^:{} prop:t
#+OPTIONS: prop:t
# This makes MathJax not work
# #+OPTIONS: tex:imagemagick
# this makes MathJax work
#+OPTIONS: tex:t
#+LATEX_CLASS: article
#+LATEX_CLASS_OPTIONS: [american]
# Setup tikz package for both LaTeX and HTML export:
#+LATEX_HEADER: \usepackage{tikz}
#+LATEX_HEADER: \usepackage{commath}
#+LaTeX_HEADER: \usepackage{pgfplots}
#+LaTeX_HEADER: \usepackage{sansmath}
#+LaTeX_HEADER: \usepackage{mathtools}
# #+HTML_MATHJAX: align: left indent: 5em tagside: left font: Neo-Euler
#+PROPERTY: header-args:latex+ :packages '(("" "tikz"))
#
#+PROPERTY: header-args:latex+ :exports results :fit yes
#
#+STARTUP: showall
#+STARTUP: align
#+STARTUP: indent
#+STARTUP: entitiespretty
#+STARTUP: logdrawer
* Test
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I'm on Emacs 25.1.1 and Org mode version 9.0.5 (9.0.5-elpaplus @ .../.emacs.d/elpa/org-plus-contrib-20170210/)