\normalsize not defined

The LaTeX error:

The font size command \normalsize is not defined:
there is probably something wrong with the class file.

reports something pretty fundamental (document base font size has not been set, something the document class does for you). It can, in principle, be a problem with the document class, but is more often caused by the user forgetting to start their document with a \documentclass command.

FAQ ID: Q-normalszmiss