---
title: "Deprecation: #101554 - Obsolete TCA MM_hasUidField"
manual: "TYPO3 Core Changelog"
version: "main"
permalink: "https://docs.typo3.org/permalink/changelog:deprecation-101554-1691480627"
source: "Changelog/13.0/Deprecation-101554-ObsoleteTCAMM_hasUidField.rst"
typo3-version: "13.0"
typo3-major: 13
type: "deprecation"
issue: 101554
forge: "https://forge.typo3.org/issues/101554"
tags: ["TCA", "NotScanned", "ext:core"]
rendered: "2026-09-18T10:44:28+00:00"
---

# Deprecation: #101554 - Obsolete TCA MM_hasUidField {#deprecation-101554-1691480627}

See [forge#101554](https://forge.typo3.org/issues/101554)

## Description {#description}

When configuring `MM` relations in TCA, the field `MM_hasUidField`
has been obsoleted: A `uid` column is only needed when `multiple`
is set to true - when a record is allowed to be selected multiple times in
a relation. In this case, the `uid` field is added automatically by the
database analyzer.

## Impact {#impact}

The TCA configuration option `MM_hasUidField` is obsolete and can be removed.

The TCA migration, which is performed during TCA warmup, will automatically
remove this option and creates according log entries, if needed.

## Affected installations {#affected-installations}

Instances with extensions using `MM` relations may be affected.

## Migration {#migration}

Remove all occurrences of php:`MM_hasUidField` from TCA. The `uid` column
is added as primary key automatically, if `multiple = true` is set, otherwise
a combined primary key of the fields `uid_local`, `uid_foreign` plus
eventually `tablenames` and `fieldname` is used.