Frequently Asked Question List for TeX

# Capacity exceeded — input levels

The error

``````! TeX capacity exceeded, sorry [text input levels=15].
``````

is caused by nesting your input too deeply. You can provoke it with the trivial (Plain TeX) file `input.tex`, which contains nothing but:

``````\input input
``````

In the real world, you are unlikely to encounter the error with a modern TeX distribution. TeTeX (used to produce the error message above) allows 15 files open for TeX input at any one time, which is improbably huge for a document generated by real human beings.

However, for those improbable (or machine-generated) situations, some distributions offer the opportunity to adjust the parameter `max_in_open` in a configuration file.

FAQ ID: Q-inputlev