Problem:
You want to compile your LaTeX file on Ubuntu using latex
or pdflatex
but you see an error message like this:
! Package babel Error: Unknown option `ngerman'. Either you misspelled it (babel) or the language definition file ngerman.ldf was not foun d. See the babel package documentation for explanation. Type H <return> for immediate help
Solution
sudo apt -y install texlive-lang-german
This will install, among many other LaTeX files, the files for the ngerman
language.