可能是在最近更新到 win10 之后，在 TeXWorks 中运行 TiKZ externalize 命令会给出缺少 shell 命令的错误消息（事实并非如此，并且最近外部化工作正常）。缺少图形的日志文件中的错误消息包含以下内容：
LaTeX 错误：索引类型“默认”未定义。
并结束于
! ==> Fatal error occurred, no output PDF file produced!
The log file for the master document contains the following:
(BoS.tex
===== 'mode=convert with system call': Invoking 'pdflatex -shell-escape -halt-o
n-error -interaction=batchmode -jobname "epistemics-figure0" "\def\tikzexternal
realjob{epistemics}\input{epistemics}"' ========
\openout3 = `epistemics.auxlock'.
runsystem(pdflatex -shell-escape -halt-on-error -interaction=batchmode -jobname
"epistemics-figure0" "\def\tikzexternalrealjob{epistemics}\input{epistemics}")
...executed.
\openout3 = `epistemics.auxlock'.
! Package tikz Error: Sorry, the system call 'pdflatex -shell-escape -halt-on-e
rror -interaction=batchmode -jobname "epistemics-figure0" "\d
最后，文件 epistemics.auxlock 包含一行：
\def \tikzexternallocked {0}
我完全被迷惑了。如能得到任何帮助我将不胜感激。