[BUG] polyglossia / \setmainlanguage broken in latest MiKTeX

[chskcau]

• I have read and acknowledged this HOWTO article:
  Submitting a MiKTeX problem report

Summary

After updating MiKTeX this morning, documents loading polyglossia and using \setmainlanguage do not compile anymore using XeLaTeX.

Example document

Input

Here is an example document showing the problem:

\documentclass{article}
\usepackage{polyglossia}
\setmainlanguage{english}
\begin{document}
\end{document}

Log output

This is XeTeX, Version 3.141592653-2.6-0.999995 (MiKTeX 24.1) (preloaded format=xelatex 2024.2.23)  23 FEB 2024 16:46
entering extended mode
 restricted \write18 enabled.
 %&-line parsing enabled.
**./test.tex
(test.tex
LaTeX2e <2023-11-01> patch level 1
L3 programming layer <2024-02-13>
(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/base\article.cls
Document Class: article 2023/05/17 v1.4n Standard LaTeX document class
(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/base\size10.clo
File: size10.clo 2023/05/17 v1.4n Standard LaTeX file (size option)
)
\c@part=\count184
\c@section=\count185
\c@subsection=\count186
\c@subsubsection=\count187
\c@paragraph=\count188
\c@subparagraph=\count189
\c@figure=\count190
\c@table=\count191
\abovecaptionskip=\skip48
\belowcaptionskip=\skip49
\bibindent=\dimen140
)
(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/polyglossia\polygl
ossia.sty
Package: polyglossia 2023/12/11 v1.66 Modern multilingual typesetting with XeLa
TeX and LuaLaTeX

(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/etoolbox\etoolbox.
sty
Package: etoolbox 2020/10/05 v2.5k e-TeX tools for LaTeX (JAW)
\etb@tempcnta=\count192
)
(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/xkeyval\xkeyval.st
y
Package: xkeyval 2022/06/16 v2.9 package option processing (HA)

(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/generic/xkeyval\xkeyval.
tex
(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/generic/xkeyval\xkvutils
.tex
\XKV@toks=\toks17
\XKV@tempa@toks=\toks18

(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/generic/xkeyval\keyval.t
ex))
\XKV@depth=\count193
File: xkeyval.tex 2014/12/03 v2.7a key=value parser (HA)
))
(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/fontspec\fontspec.
sty
(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/l3packages/xparse\
xparse.sty
(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/l3kernel\expl3.sty
Package: expl3 2024-02-13 L3 programming layer (loader) 

(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/l3backend\l3backen
d-xetex.def
File: l3backend-xetex.def 2024-01-04 L3 backend support: XeTeX
\g__graphics_track_int=\count194
\l__pdf_internal_box=\box51
\g__pdf_backend_object_int=\count195
\g__pdf_backend_annotation_int=\count196
\g__pdf_backend_link_int=\count197
))
Package: xparse 2024-02-13 L3 Experimental document command parser
)
Package: fontspec 2024/02/13 v2.9a Font selection for XeLaTeX and LuaLaTeX

(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/fontspec\fontspec-
xetex.sty
Package: fontspec-xetex 2024/02/13 v2.9a Font selection for XeLaTeX and LuaLaTe
X
\l__fontspec_script_int=\count198
\l__fontspec_language_int=\count199
\l__fontspec_strnum_int=\count266
\l__fontspec_tmp_int=\count267
\l__fontspec_tmpa_int=\count268
\l__fontspec_tmpb_int=\count269
\l__fontspec_tmpc_int=\count270
\l__fontspec_em_int=\count271
\l__fontspec_emdef_int=\count272
\l__fontspec_strong_int=\count273
\l__fontspec_strongdef_int=\count274
\l__fontspec_tmpa_dim=\dimen141
\l__fontspec_tmpb_dim=\dimen142
\l__fontspec_tmpc_dim=\dimen143

(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/base\fontenc.sty
Package: fontenc 2021/04/29 v2.0v Standard LaTeX package
)
(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/fontspec\fontspec.
cfg)))
(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/generic/iftex\iftex.sty
Package: iftex 2022/02/03 v1.0f TeX engine tests
)
\xpg@normalclass=\XeTeXcharclass1

(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/polyglossia\gloss-
latex.lde
Package: gloss-latex 2023/12/11 v1.66 polyglossia: module for default language
)
Package polyglossia Info: Default language is latex.
)
(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/polyglossia\gloss-
english.ldf
File: gloss-english.ldf polyglossia: module for English
Package polyglossia Info: Option: English, variant=american.

! Use of \__prop_put_linked:wnnN doesn't match its definition.
<recently read> ...alias@keyvals@english@american 
                                                  
l.132 ...as@values{english}{variant}{us}{american}
                                                  
If you say, e.g., `\def\a1{...}', then you must always
put `1' after `\a', since control sequence names are
made up of letters only. The macro here has not been
followed by the required stuff, so I'm ignoring it.


! LaTeX Error: Missing \begin{document}.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                                  
l.132 ...as@values{english}{variant}{us}{american}
                                                  
You're in trouble here.  Try typing  <return>  to proceed.
If that doesn't work, type  X <return>  to quit.

)
Package polyglossia Info: Default language is english.
 (test.aux)
\openout1 = `test.aux'.

LaTeX Font Info:    Checking defaults for OML/cmm/m/it on input line 4.
LaTeX Font Info:    ... okay on input line 4.
LaTeX Font Info:    Checking defaults for OMS/cmsy/m/n on input line 4.
LaTeX Font Info:    ... okay on input line 4.
LaTeX Font Info:    Checking defaults for OT1/cmr/m/n on input line 4.
LaTeX Font Info:    ... okay on input line 4.
LaTeX Font Info:    Checking defaults for T1/cmr/m/n on input line 4.
LaTeX Font Info:    ... okay on input line 4.
LaTeX Font Info:    Checking defaults for TS1/cmr/m/n on input line 4.
LaTeX Font Info:    Trying to load font information for TS1+cmr on input line 4
.

(C:\Users\USER\AppData\Local\Programs\MiKTeX\tex/latex/base\ts1cmr.fd
File: ts1cmr.fd 2023/04/13 v2.5m Standard LaTeX font definitions
)
LaTeX Font Info:    ... okay on input line 4.
LaTeX Font Info:    Checking defaults for TU/lmr/m/n on input line 4.
LaTeX Font Info:    ... okay on input line 4.
LaTeX Font Info:    Checking defaults for OMX/cmex/m/n on input line 4.
LaTeX Font Info:    ... okay on input line 4.
LaTeX Font Info:    Checking defaults for U/cmr/m/n on input line 4.
LaTeX Font Info:    ... okay on input line 4.

Package fontspec Info: Adjusting the maths setup (use [no-math] to avoid
(fontspec)             this).

\symlegacymaths=\mathgroup4
LaTeX Font Info:    Overwriting symbol font `legacymaths' in version `bold'
(Font)                  OT1/cmr/m/n --> OT1/cmr/bx/n on input line 4.
LaTeX Font Info:    Redeclaring math accent \acute on input line 4.
LaTeX Font Info:    Redeclaring math accent \grave on input line 4.
LaTeX Font Info:    Redeclaring math accent \ddot on input line 4.
LaTeX Font Info:    Redeclaring math accent \tilde on input line 4.
LaTeX Font Info:    Redeclaring math accent \bar on input line 4.
LaTeX Font Info:    Redeclaring math accent \breve on input line 4.
LaTeX Font Info:    Redeclaring math accent \check on input line 4.
LaTeX Font Info:    Redeclaring math accent \hat on input line 4.
LaTeX Font Info:    Redeclaring math accent \dot on input line 4.
LaTeX Font Info:    Redeclaring math accent \mathring on input line 4.
LaTeX Font Info:    Redeclaring math symbol \colon on input line 4.
LaTeX Font Info:    Redeclaring math symbol \Gamma on input line 4.
LaTeX Font Info:    Redeclaring math symbol \Delta on input line 4.
LaTeX Font Info:    Redeclaring math symbol \Theta on input line 4.
LaTeX Font Info:    Redeclaring math symbol \Lambda on input line 4.
LaTeX Font Info:    Redeclaring math symbol \Xi on input line 4.
LaTeX Font Info:    Redeclaring math symbol \Pi on input line 4.
LaTeX Font Info:    Redeclaring math symbol \Sigma on input line 4.
LaTeX Font Info:    Redeclaring math symbol \Upsilon on input line 4.
LaTeX Font Info:    Redeclaring math symbol \Phi on input line 4.
LaTeX Font Info:    Redeclaring math symbol \Psi on input line 4.
LaTeX Font Info:    Redeclaring math symbol \Omega on input line 4.
LaTeX Font Info:    Redeclaring math symbol \mathdollar on input line 4.
LaTeX Font Info:    Redeclaring symbol font `operators' on input line 4.
LaTeX Font Info:    Encoding `OT1' has changed to `TU' for symbol font
(Font)              `operators' in the math version `normal' on input line 4.
LaTeX Font Info:    Overwriting symbol font `operators' in version `normal'
(Font)                  OT1/cmr/m/n --> TU/lmr/m/n on input line 4.
LaTeX Font Info:    Encoding `OT1' has changed to `TU' for symbol font
(Font)              `operators' in the math version `bold' on input line 4.
LaTeX Font Info:    Overwriting symbol font `operators' in version `bold'
(Font)                  OT1/cmr/bx/n --> TU/lmr/m/n on input line 4.
LaTeX Font Info:    Overwriting symbol font `operators' in version `normal'
(Font)                  TU/lmr/m/n --> TU/lmr/m/n on input line 4.
LaTeX Font Info:    Overwriting math alphabet `\mathit' in version `normal'
(Font)                  OT1/cmr/m/it --> TU/lmr/m/it on input line 4.
LaTeX Font Info:    Overwriting math alphabet `\mathbf' in version `normal'
(Font)                  OT1/cmr/bx/n --> TU/lmr/b/n on input line 4.
LaTeX Font Info:    Overwriting math alphabet `\mathsf' in version `normal'
(Font)                  OT1/cmss/m/n --> TU/lmss/m/n on input line 4.
LaTeX Font Info:    Overwriting math alphabet `\mathtt' in version `normal'
(Font)                  OT1/cmtt/m/n --> TU/lmtt/m/n on input line 4.
LaTeX Font Info:    Overwriting symbol font `operators' in version `bold'
(Font)                  TU/lmr/m/n --> TU/lmr/b/n on input line 4.
LaTeX Font Info:    Overwriting math alphabet `\mathit' in version `bold'
(Font)                  OT1/cmr/bx/it --> TU/lmr/b/it on input line 4.
LaTeX Font Info:    Overwriting math alphabet `\mathsf' in version `bold'
(Font)                  OT1/cmss/bx/n --> TU/lmss/b/n on input line 4.
LaTeX Font Info:    Overwriting math alphabet `\mathtt' in version `bold'
(Font)                  OT1/cmtt/m/n --> TU/lmtt/b/n on input line 4.
LaTeX Info: Redefining \rmfamily on input line 4.
LaTeX Info: Redefining \sffamily on input line 4.
LaTeX Info: Redefining \ttfamily on input line 4.

[1

] (test.aux)
 ***********
LaTeX2e <2023-11-01> patch level 1
L3 programming layer <2024-02-13>
 ***********
 ) 
Here is how much of TeX's memory you used:
 4408 strings out of 409556
 127918 string characters out of 5770975
 1917650 words of memory out of 5000000
 26562 multiletter control sequences out of 15000+600000
 558085 words of font info for 38 fonts, out of 8000000 for 9000
 1348 hyphenation exceptions out of 8191
 93i,5n,107p,297b,146s stack positions out of 10000i,1000n,20000p,200000b,200000s

Output written on test.pdf (1 page).

[edocevoli]

I don't think this is a MiKTeX-specific bug.