FatalCommands & Packages
Environment Undefined
! LaTeX Error: Environment XXX undefined.
What this error means
You tried to use \begin{envname} but LaTeX has no definition for that environment. Usually caused by a missing package or a typo in the environment name.
FormaTeX smart compile
FormaTeX smart compile detects AMS math environments and automatically adds \usepackage{amsmath} to the preamble before compiling.
Common causes
- The package that provides the environment is not loaded
- Typo in the environment name (e.g. \begin{aligend} instead of \begin{aligned})
- Using an environment defined in a newer LaTeX version
How to fix it
Add the required \usepackage to the preamble. The amsmath package provides align, aligned, gather, multline, and most math environments. The enumitem package extends list environments.
Code examples
Causes the error
\documentclass{article}
% Missing \usepackage{amsmath}
\begin{document}
\begin{align}
E &= mc^2 \\
F &= ma
\end{align}
\end{document}Fixed
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
E &= mc^2 \\
F &= ma
\end{align}
\end{document}Related errors
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