ddp build failed

Latexmk: Examining 'release-notes.log'
Latexmk: Index file 'release-notes.idx' was written
Latexmk: Log file says output to 'release-notes.pdf'
Latexmk: All targets () are up-to-date

make[1]: Leaving directory '/srv/www.debian.org/release-notes/release-notes/build/es/pdf'
echo "* Starting pdf build for: fa"
* Starting pdf build for: fa
sphinx-build -W -b latex -D language=fa -d build/fa source build/fa/pdf
Running Sphinx v5.3.0
loading translations [fa]... done
making output directory... done

Warning, treated as error:
no Babel option known for language 'fa'
make: *** [Makefile:107: build/fa/pdf/release-notes.pdf] Error 2