---
title: "Breaking: #77919 - Changed DateTime::ISO8601 to DateTime::ATOM"
manual: "TYPO3 Core Changelog"
version: "main"
permalink: "https://docs.typo3.org/permalink/changelog:breaking-77919"
source: "Changelog/8.4/Breaking-77919-ChangedDateTimeISO8601ToDateTimeATOM.rst"
modified: "2026-09-15T10:46:36+00:00"
---

# Breaking: #77919 - Changed DateTime::ISO8601 to DateTime::ATOM

See [forge#77919](https://forge.typo3.org/issues/77919)

## Description

The format `DateTime::ISO8601` is not compatible with ISO-8601, but is left this way for
backward compatibility reasons. The constant `DateTime::ATOM` or `DATE_ATOM` is used
instead when rendering JsonViews via Extbase.

See [https://php.net/manual/en/class.datetime.php#datetime.constants.iso8601](https://php.net/manual/en/class.datetime.php#datetime.constants.iso8601) for more information