Missing \endcsname in Tikzcd

Question

I have a problem with tikzcd.

I want to make the following diagram:

\begin{tikzcd}
G \ar[d, two heads, swap, "\varphi_1"] \ar[r, "\varphi_2"] & F_2 \\
F_1 \ar[ur, dashed, swap, "\varphi"] &
\end{tikzcd}

When I put it in a separate document, it works just as it should. But when I put it into a full document and compile it with MikTex (using Texworks) I get the following error:

! Missing \endcsname inserted.
<to be read again> 
               \varphi 
l.260 \end{tikzcd}

Any ideas what I can do with it?

Answer 1

Based on your name, I suspect your document is something like

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[polish]{babel}

\usepackage{tikz-cd}

\begin{document}

\title{Tytuł}
\author{Paweł Piwek}

\maketitle

\begin{tikzcd}
G \ar[d, two heads, swap, "\varphi_1"] \ar[r, "\varphi_2"] & F_2 \\
F_1 \ar[ur, dashed, swap, "\varphi"] &
\end{tikzcd}

\end{document}

In this case, the first error message, which is the one you should report, is

! Argument of \language@active@arg" has an extra }.
<inserted text> 
                \par 
l.18 \end{tikzcd}

and this is a babel problem. Fix it with \usetikzlibrary{babel}.

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[polish]{babel}

\usepackage{tikz-cd}
\usetikzlibrary{babel}

\begin{document}

\title{Tytuł}
\author{Paweł Piwek}

\maketitle

\begin{tikzcd}
G \ar[d, two heads, swap, "\varphi_1"] \ar[r, "\varphi_2"] & F_2 \\
F_1 \ar[ur, dashed, swap, "\varphi"] &
\end{tikzcd}

\end{document}

Answer 2

For me the problems were caused by loading Babel with ngerman, i.e. \usepackage[ngerman]{babel}. Unfortunately, \usetikzlibrary{babel} suggested in the other answer did not fix the problem.

The solution which worked for me was to make " inactive again:

\begin{document}

  % Then very soonish execute the following:
  \shorthandoff{"}

  ...
...

Answer 3

I wanted to just add this in as a comment, but I'm new here. I thought it was worth mentioning that I encountered the same error message while using square brackets in tikzcd:

\begin{tikzcd}[row sep=tiny]

[ \Sigma^j X, \Sigma^j Y ]  \arrow{dr}{\phi_j} \arrow{dd}{\Sigma^{i}}\\

& Z \\

[ \Sigma^{i+j} X, \Sigma^{i+j} Y ] \arrow{ur}[below]{\phi_{i+j}}

\end{tikzcd}

It was solved by replacing [ and ] with \left[ and \right].

Answer 4

I had a very similar problem (Missing \endcsname inserted.) with a Tikz figure.

None of the above answers worked (even though I am using babel), so, after lots of searching, I commented out my package imports one by one, and found that the siunitx package singlehandedly caused the Tikz figure to crash at compilation. Might help someone out with the same error message and usage of Tikz.