---
title: "Breaking: #24900 - Remove $TYPO3_CONF_VARS[SYS][compat_version] option"
manual: "TYPO3 Core Changelog"
version: "main"
permalink: "https://docs.typo3.org/permalink/changelog:breaking-24900"
source: "Changelog/7.1/Breaking-24900-CompatVersion-Setting-Removed.rst"
modified: "2026-09-14T09:47:36+00:00"
---

# Breaking: #24900 - Remove $TYPO3_CONF_VARS\[SYS\]\[compat_version\] option

See [forge#24900](https://forge.typo3.org/issues/24900)

## Description

The option `$TYPO3_CONF_VARS[SYS][compat_version]`, which was modified on update in the Install Tool wizard,
has been removed.

Any checks on `GeneralUtility::compat_version` are now made against the common constant `TYPO3_branch` instead of
the former TYPO3_CONF_VARS option.

## Impact

Any usage of `$TYPO3_CONF_VARS[SYS][compat_version]` where the value is different than `TYPO3_branch` will result
in unexpected behaviour.

TypoScript conditions which check for older compat_version will have different behaviour now.

## Affected installations

Any installation where `$TYPO3_CONF_VARS[SYS][compat_version]` was not set to the currently running version
or where the value of compat_version was used to simulate behaviour of an older version.
E.g. TypoScript conditions or `GeneralUtility::compat_version` in extensions.

## Migration

Remove any direct usage of the option, and use the "compat_version" method within `GeneralUtility` as well as the
TypoScript condition "compat_version" which gives more accurate results.