If you try to use an environment which LaTeX does not recognize, you will generate an error message like the one below:

main.tex, line 5

See the LaTeX manual or LaTeX Companion for explanation. Type H <return> for immediate help. ... l.5 \begin{equation*} Your command was ignored. Type I <command> <return> to replace it with another command, or <return> to continue without it.

**You have forgotten to load a package**

A common cause of this error is when you are trying to use an environment which is part of a specific package, but you have forgotten to load the package in your preamble. An example of this is the ** align** environment. The

`align`

`amsmath`

`align`

`\usepackage{amsmath}`

% In your preamble \usepackage{amsmath} % In your main .tex file \begin{align} 2x + 3y &= 7\\ 5x - 2y &= 2 \end{align}

If you do not include ** \usepackage{amsmath}** in your preamble, you will generate an error message.

**You have spelled the environment incorrectly:**

Another common example of this error is when an environment is spelled correctly. An example of this mistake is shown below:

\begin{lisQ} \item This is a list item \item This is another list item \end{lisQ}

An error will appear here, as the ** list** environment was mistakenly written as

`lisQ`

**Environment does not exist**

One other way in which this error can appear is if you attempt to use an environment which does not exist. To learn more about the allowed environments in LaTeX, as well as how to create your own, check out our documentation.

- Creating a document in Overleaf
- Uploading a project
- Copying a project
- Creating a project from a template
- Including images in Overleaf
- Exporting your work from Overleaf
- Working offline in Overleaf
- Using Track Changes in Overleaf
- Using bibliographies in Overleaf
- Sharing your work with others
- Debugging Compilation timeout errors
- How-to guides

- Creating your first LaTeX document
- Choosing a LaTeX Compiler
- Paragraphs and new lines
- Bold, italics and underlining
- Lists
- Errors

- Mathematical expressions
- Subscripts and superscripts
- Brackets and Parentheses
- Fractions and Binomials
- Aligning Equations
- Operators
- Spacing in math mode
- Integrals, sums and limits
- Display style in math mode
- List of Greek letters and math symbols
- Mathematical fonts

- Inserting Images
- Tables
- Positioning Images and Tables
- Lists of Tables and Figures
- Drawing Diagrams Directly in LaTeX
- TikZ package

- Bibliography management in LaTeX
- Bibliography management with biblatex
- Biblatex bibliography styles
- Biblatex citation styles
- Bibliography management with natbib
- Natbib bibliography styles
- Natbib citation styles
- Bibliography management with bibtex
- Bibtex bibliography styles

- International language support
- Quotations and quotation marks
- Arabic
- Chinese
- French
- German
- Greek
- Italian
- Japanese
- Korean
- Portuguese
- Russian
- Spanish

- Sections and chapters
- Table of contents
- Cross referencing sections and equations
- Indices
- Glossaries
- Nomenclatures
- Management in a large project
- Multi-file LaTeX projects
- Hyperlinks

- Lengths in LaTeX
- Headers and footers
- Page numbering
- Paragraph formatting
- Line breaks and blank spaces
- Text alignment
- Page size and margins
- Single sided and double sided documents
- Multiple columns
- Counters
- Code listing
- Code Highlighting with minted
- Using colours in LaTeX
- Footnotes
- Margin notes

- Theorems and proofs
- Chemistry formulae
- Feynman diagrams
- Molecular orbital diagrams
- Chess notation
- Knitting patterns
- CircuiTikz package
- Pgfplots package
- Typing exams in LaTeX
- Knitr
- Attribute Value Matrices