# \micro in package siunitx stopped working

Using the \micro command in siunitx worked fine some months ago. But suddenly, maybe caused by software updates, some fellows and me aren't able to use \micro in siunitx.

There is no error, the \mu is simply not displayed in the generated PDF-file.

We are currently using dirty workarounds such as using 10^{-6} or \upgreek instead, but we are very interested in solving the problem.

We are using LuaLatex as Latex-engine on different systems (macOs and different Ubuntu distros).

Edit: I am using LuaLatex Version 1.0.4 (TeX Live 2017); my minimal code example, causing the error, which was working fine some months ago, is the following:

\documentclass{scrartcl}
\usepackage{polyglossia}
\setmainlanguage{german}
\usepackage{unicode-math}
\usepackage{siunitx}
\begin{document}\si{\micro}\end{document}

• Please give specific examples, i.e., actual code, which "worked" at some point in the past and have now "stopped working". Please also tell us which version of LuaLaTeX you use; this piece of information is provided in the first row of the log file. – Mico Apr 24 '18 at 5:05
• Cannot reproduce \documentclass{article} \usepackage{siunitx} \begin{document} \si{\micro} \end{document} (screenshot). – Henri Menke Apr 24 '18 at 6:03
• \documentclass{article} \usepackage{siunitx} \begin{document} \si{\micro} \end{document} is fine with both pdflatex and lualatex with TL2017. – NBur Apr 24 '18 at 6:41
• I edited my question, I have simplified my usual header as far as possible, the error seems to be caused somehow by unicode-math – julandi Apr 24 '18 at 6:49
• I can reproduce the problem, it is due to a (resolved) bug in unicode-math. It will be gone with TL2018. See tex.stackexchange.com/a/411573/2388. – Ulrike Fischer Apr 24 '18 at 6:58

From this answer, just add a \sisetup:

\documentclass{scrartcl}
\usepackage{polyglossia}
\setmainlanguage{german}
\usepackage{unicode-math}
\usepackage{siunitx}
\sisetup{math-micro=\text{µ},text-micro=µ}
\begin{document}\si{\micro}\end{document}

• Thanks, that worked for me. But I would like to understand, why the exact same code was working last year? What (and why) was changed in the LuaLatex-software? – julandi Apr 24 '18 at 7:01
• Really I can't answer this question! The naive way is another question: didn't you change your preamble adding the unicode-math? But you've already said exact same code – NBur Apr 24 '18 at 7:09
• I have double-checked some of my old documents, with the exact same header, without using sisetup and I took a look in my old log-files, I was using the exact same Version of LuaLatex back then (LuaLatex, 1.0.4 (TeX Live 2017) (format=lualatex 2017.6.25) 14 AUG 2017 10:59, the only difference to today is: (format=lualatex 2018.4.19) 24 APR 2018 08:59 and I am not really sure, what this exactly means) – julandi Apr 24 '18 at 7:14
• And, double-checked it too, we were using the same header back then. unicode-math was included in my preamble. When I recompile my old files without adding \sisetup every \micro disappears. Magic! :) – julandi Apr 24 '18 at 7:18