Fixing common errors
What the most frequent LaTeX messages mean and how to fix them.
Undefined control sequence
LaTeX does not know a command — usually a typo (\textbff) or a command whose package is not loaded (e.g. \toprule needs \usepackage{booktabs}). The log in CiteTeX names the package to add.
Missing $ inserted
A math-only symbol such as _, ^ or \alpha was used outside math. Put it in math ($x_1$), or escape it in text: file\_name.
File not found
An image, \input file or .bib named in the document is not in the project, or the path or capitalisation differs (Figures/ vs figures/). Upload it with Add files, keeping the folder names.
?? instead of numbers, [?] instead of citations
A \ref points to a label that does not exist, or a \cite key is not in any .bib. Check the spelling of the label or key. CiteTeX compiles enough times for references to settle, so lasting ?? always means a missing label.
Overfull \hbox
Something is wider than the line: a long word or URL, a wide table, or an image without a width. Small overflows are harmless; for images add width=\linewidth (CiteTeX offers a one-click fix).