---
title: "TYPO3 Exception 1596980032"
manual: "TYPO3 Exceptions"
version: "main"
permalink: "https://docs.typo3.org/permalink/t3exceptions:typo3-exception-1596980032"
source: "Exceptions/1596980032.rst"
modified: "2026-09-16T07:39:08+00:00"
---

# TYPO3 Exception 1596980032

> [!NOTE]
> Below, the TYPO3 community may have provided additional information or
> solutions for this exception. However, these may or may not apply to your
> particular case. If you can provide more information, you should come back
> here and add your experience and solution steps to this issue once you have
> resolved it.
>
> General TYPO3 troubleshooting tips can be found in the *Troubleshooting*
> section in the menu. You can also ask questions and receive support in the
> [TYPO3 Questions category on talk.typo3.org](https://talk.typo3.org/c/typo3-questions/).
>
> To add your experience, click "Edit on GitHub" above and follow the
> ["Edit on GitHub" workflow](https://docs.typo3.org/m/typo3/docs-how-to-document/main/en-us/Howto/EditOnGithub.html#docs-contribute-github-method).
> Also check out
> [our tip on Coding Style and reST](https://docs.typo3.org/permalink/t3exceptions:tip-about-rest-coding-style).

## InvalidArgumentException:  A cache identifier was not set

When debuging the corresponding cache.definition might look like this:

```php
'' => array('groups' => array('pages', 'all'))
```

This error can break the backend and frontend.

### Background

Before TYPO3 version 10 it was common that the variable `$_EXTKEY` was
replaced automatically by the extension key of the corresponding
extension.

This has changed and the variable either has to be defined or the
extension key automatically applied.

As the variable `$_EXTKEY` was undefined, the array key for
the cache definition was empty.

The error was therefore caused by an incomplete extension-update.

### Solution

Search in all extensions for usage of `$_EXTKEY` in the file
`ext_localconf.php`.

If the variable is used but not defined in that file, define it in the
beginning or replace it by the extension key.