我有同样的问题https://tex.stackexchange.com/questions/295126。但就我而言，反复运行两个 MiKTeX 更新程序并不能解决问题。我还尝试运行两个包管理器，同步数据库，然后再次运行两个更新程序。我可以在日志中看到我的 LaTeX3 包已过时，但为什么更新程序不更新它们呢？
梅威瑟：
\documentclass{article}
\usepackage{fontspec}
\begin{document}
Hi
\end{document}
日志：
This is XeTeX, Version 3.14159265-2.6-0.99992 (MiKTeX 2.9) (preloaded format=xelatex 2016.4.25) 25 APR 2016 13:39
entering extended mode
**"D:/Marci/Google Drive/tex/nodecolon.tex"
("D:/Marci/Google Drive/tex/nodecolon.tex"
LaTeX2e <2016/03/31>
Babel <3.9q> and hyphenation patterns for 70 language(s) loaded.
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Document Class: article 2014/09/29 v1.4h Standard LaTeX document class
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File: size10.clo 2014/09/29 v1.4h Standard LaTeX file (size option)
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Package: expl3 2013/10/13 v4597 L3 Experimental code bundle wrapper
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Package: l3basics 2013/07/28 v4581 L3 Basic definitions
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Package: l3expan 2013/08/17 v4584 L3 Argument expansion
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(C:\Users\Marci\AppData\Roaming\MiKTeX\2.9\tex\latex\l3kernel\l3tl.sty
Package: l3tl 2013/09/16 v4592 L3 Token lists
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Package: l3keys 2013/07/28 v4581 L3 Experimental key-value interfaces
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(C:\Users\Marci\AppData\Roaming\MiKTeX\2.9\tex\latex\l3kernel\l3fp.sty
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! Undefined control sequence.
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