# Entity not defined

Source: https://xmlvalid.com/errors/entity-not-defined

> The document uses a named entity, like  , that XML does not know.

Example message: `Entity 'nbsp' not defined`

## Why it happens

- HTML entities copied into XML: ` `, `©`, `é`, `—`… XML defines only five: `<`, `>`, `&`, `"` and `'`.
- An entity declared in a DTD that is not loaded.

## How to fix it

- Replace the entity with the character itself (the document is UTF-8 by default), or with a numeric reference: ` ` for a non-breaking space, `©` for ©. If the entity belongs to a DTD, declare that DTD in the document.

## Example that fails

```xml
<p>Price:&nbsp;10</p>
```

## Fixed

```xml
<p>Price:&#160;10</p>
```