---
title: "Breaking: #21638 - AbstractUserAuthentication::lockIP property removed"
manual: "TYPO3 Core Changelog"
version: "main"
permalink: "https://docs.typo3.org/permalink/changelog:breaking-21638"
source: "Changelog/10.0/Breaking-21638-LockIPPropertyRemoved.rst"
typo3-version: "10.0"
typo3-major: 10
type: "breaking"
issue: 21638
forge: "https://forge.typo3.org/issues/21638"
tags: ["Backend", "Frontend", "LocalConfiguration", "NotScanned"]
rendered: "2026-09-24T12:29:17+00:00"
---

# Breaking: #21638 - AbstractUserAuthentication::lockIP property removed {#breaking-21638}

See [forge#21638](https://forge.typo3.org/issues/21638)

## Description {#description}

The IP-locking-functionality is extended from IPv4 only to now also support IPv6. A separate IpLocker-functionality was added.

The public property `lockIP` in `\TYPO3\CMS\Core\Authentication\AbstractUserAuthentication` is now removed.
It usually shouldn't have been accessed directly and supported IPv4 only.

## Impact {#impact}

Extensions relying on `lockIP` won't be able to perform their task anymore.
This might for example be the case when `lockIP` was set dynamically, depending on the REMOTE_ADDR.

## Affected Installations {#affected-installations}

Every 3rd party extension depending on the formerly public `lockIP` property is affected.

## Migration {#migration}

Set `lockIP` and `lockIPv6` in `TYPO3_CONF_VARS` \- for FE or BE depending on the use case.
Use the new `\TYPO3\CMS\Core\Authentication\IpLocker` API.