How to fix LaTeX \glqq or \grqq error 'Undefined control sequence'

Problem:

You have LaTeX code containing \glqq and/or \grqq like

\documentclass{scrartcl}

\begin{document}
\glqq Test\grqq
\end{document}

but when you try to compile it, you see an error message like this:

! Undefined control sequence.
l.5 \glqq
          Test\grqq
? 

Solution

In order to use \glqq or \grqq you need to include

\usepackage[ngerman]{babel}

after your \documentclass declaration.

In case you want to use another language, use the correct language specifier instead of ngerman.