`lang: fr-CA` causes render to pdf format to fail

[ekatko1]

I have:

• searched the issue tracker for similar issues
• installed the latest version of Quarto CLI
• formatted my issue following the Bug Reports guide

Bug description

Wehn I try to render a document to pdf with lang: fr-CA set in the YAML options, the render process outputs an error that is incomprehensible to me.

Steps to reproduce

Create quarto document (pdf-out.qmd):

---
lang: fr-CA
format: pdf
---

Salut, tabarnak!

Actual behavior

Rendering produces the following error:

$ quarto render pdf-out.qmd
pandoc
  to: latex
  output-file: pdf-out.tex
  standalone: true
  pdf-engine: lualatex
  variables:
    graphics: true
    tables: true
  default-image-extension: pdf

metadata
  documentclass: scrartcl
  classoption:
    - DIV=11
    - numbers=noendperiod
  papersize: letter
  header-includes:
    - \KOMAoption{captions}{tableheading}
  block-headings: true
  engines:
    - path: C:\Users\Egor\AppData\Local\Programs\Quarto\share\extension-subtrees\julia-engine\_extensions\julia-engine\julia-engine.js
  lang: fr-CA


Rendering PDF
running lualatex - 1
  This is LuaHBTeX, Version 1.24.0 (TeX Live 2026)
   restricted system commands enabled.

updating tlmgr

updating existing packages
ERROR:
compilation failed- error
Undefined control sequence.
\__hook begindocument ...fter {\bbl@main@language
                                                  }\ifbbl@single \renewcomma...
l.176 \begin{document}



see pdf-out.log for more information.
WARN: Error encountered when rendering files

Expected behavior

Compile normally, as is the case for lang: fr and lang: en-GB.

Interestingly, setting lang: de-CH produces a different error:

$ quarto render pdf-out-de.qmd
pandoc
  to: latex
  output-file: pdf-out-de.tex
  standalone: true
  pdf-engine: lualatex
  variables:
    graphics: true
    tables: true
  default-image-extension: pdf

metadata
  documentclass: scrartcl
  classoption:
    - DIV=11
    - numbers=noendperiod
  papersize: letter
  header-includes:
    - \KOMAoption{captions}{tableheading}
  block-headings: true
  engines:
    - path: C:\Users\Egor\AppData\Local\Programs\Quarto\share\extension-subtrees\julia-engine\_extensions\julia-engine\julia-engine.js
  lang: de-CH


Rendering PDF
running lualatex - 1
  This is LuaHBTeX, Version 1.24.0 (TeX Live 2026)
   restricted system commands enabled.

updating tlmgr

updating existing packages
ERROR:
compilation failed- error
Package babel Error: You haven't defined the language 'ngerman' yet.
(babel)                Perhaps you misspelled it or your installation
(babel)                is not complete.

See the babel package documentation for explanation.
Type  H <return>  for immediate help.
 ...

l.176 \begin{document}



see pdf-out-de.log for more information.
WARN: Error encountered when rendering files

Your environment

• IDE: RStudio 2026.01.1 Build 403
• OS: Windows 11 Pro

Quarto check output

$ quarto check
Quarto 1.10.2
[>] Checking environment information...
      Quarto cache location: C:\Users\Egor\AppData\Local\quarto
[>] Checking versions of quarto binary dependencies...
      Pandoc version 3.8.3: OK
      Dart Sass version 1.87.0: OK
      Deno version 2.4.5: OK
      Typst version 0.14.2: OK
[>] Checking versions of quarto dependencies......OK
[>] Checking Quarto installation......OK
      Version: 1.10.2
      Path: C:\Users\Egor\AppData\Local\Programs\Quarto\bin
      CodePage: 1252

[>] Checking tools....................OK
      TinyTeX: v2026.04
      Chromium (deprecated): (not installed)
      Chrome Headless Shell: (not installed)
      VeraPDF: (not installed)

[>] Checking LaTeX....................OK
      Using: TinyTex
      Path: C:\Users\Egor\AppData\Roaming\TinyTeX\bin\windows\
      Version: 2026

[>] Checking Chrome Headless....................OK
      Using: Chrome found on system
      Path: C:\Program Files\Google\Chrome\Application\chrome.exe
      Source: Windows Registry

[>] Checking basic markdown render....OK

[>] Checking R installation...........OK
      Version: 4.5.2
      Path: C:/PROGRA~1/R/R-45~1.2
      LibPaths:
        - C:/Users/Egor/AppData/Local/R/win-library/4.5
        - C:/Program Files/R/R-4.5.2/library
      knitr: 1.51
      rmarkdown: 2.31

[>] Checking Knitr engine render......OK

[>] Checking Python 3 installation....OK
      Version: 3.14.3
      Path: C:/Users/Egor/AppData/Local/Python/pythoncore-3.14-64/python.exe
      Jupyter: (None)

      Jupyter is not available in this Python installation.
      Install with py -m pip install jupyter

[mcanouil]

The issue is that canadien is set as document class option instead of canadian, but I don't know what is creating this mapping.

[mcanouil]

Workaround:

---
lang: fr-CA
babel-lang: canadian
format: pdf
keep-tex: true
---

Salut, tabarnak!