# siunitx package causes errors when using \bar

As the title says, when I use the \bar macro for the pressure unit I get a "Missing { or forgotten \endgroup error". The minimum (not) working example is given here:

\documentclass{article}
\usepackage{siunitx}
\begin{document}
$\SI{10}{\bar}$
\end{document}


LaTeX seems to not recognize the latter }. The Error message says:

! Missing { inserted.
\egroup
l.6 $\SI{10}{\bar}$
A left brace was mandatory here, so I've put one in.
You might want to delete and/or insert some corrections
so that I will find a matching right brace soon.
(If you're confused by all this, try typing I}' now.)
! Missing } inserted.
<inserted text>
}
l.6 $\SI{10}{\bar}$
I've inserted something that you may have forgotten.
(See the <inserted text> above.)
With luck, this will get me unwedged. But if you
really didn't forget anything, try typing 2' now; then
my insertion and my current dilemma will both disappear.
[1
{C:/Users/lenna/AppData/Local/MiKTeX/pdftex/config/pdftex.map}]
(troubleshoot.aux) )


However, when using \meter instead of \bar it does compile and give me the expected output. Even though bar is not an SI unit it is listed in the documentation and it has also worked on previous occasions. I am aware that this MWE could will probably function anywhere else than on my computer, so here is what I work with: MikTex 21.3 and TeXMaker 5.0.4.

Also, when I try to compile my thesis it throws up errors of this kind:

! Undefined control sequence.
<argument> \glo@symb:a@desc
l.5 ...tentrycounter[]{page}\glsnumberformat{34}}}
%
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., \hobx'), type I' and the correct
spelling (e.g., I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.


There seems to be an additional clash with the glossaries package...

Someone please help me, I have tried everything I can and don't know where the problem lies.

• miktex is a bit behind with the siunitx updates. In a current siunitx you would get a better error message, along with this help: "The BIPM have removed this unit from the SI Brochure. You will need to define it yourself using \DeclareSIUnit.". Consider if you really want to use a deprecated unit, and if yes define it. – Ulrike Fischer May 25 at 8:13
• If the problem (I am not sure about of the second one) is from the updating of siuntix you can try to use \usepackage{siunitx}[=v2]` in a pinch... – Rmano May 25 at 9:39
• your glossary question is not answerable without a complete example. Better open a new question for it. – Ulrike Fischer May 25 at 9:48
• Note that this is much the same as github.com/josephwright/siunitx/issues/446 in concept terms - I don't have to like the removal of 'bar', I just have to have a consistent position for the package – Joseph Wright May 25 at 9:50