--- title: "ext_emconf.php (Deprecated)" manual: "TYPO3 Explained" version: "14.3" permalink: "https://docs.typo3.org/permalink/t3coreapi:ext-emconf-php@14.3" source: "ExtensionArchitecture/FileStructure/ExtEmconf.rst" rendered: "2026-10-01T15:20:05+00:00" --- # `ext_emconf.php` (Deprecated) {#ext-emconf-php} Using the ext_emconf.php file in extensions is deprecated. TYPO3 extensions that still ship an ext_emconf.php file but do not declare future compatibility to omit this file will trigger a deprecation message during cache warm-up. version and dependency metadata should now be defined in the extension's composer.json file. The file may still need to be kept for compatibility with third-party tools such as TYPO3 TER and Tailor. For older ext_emconf.php documentation see. ## Migration from `ext_emconf.php` to `composer.json` {#ext-emconf-php-migration} Use of `ext_emconf.php` in extensions has been deprecated ([Deprecation #108345](https://docs.typo3.org/c/typo3/cms-core/main/en-us/Changelog/14.2/Deprecation-108345-Deprecation-of-ext-emconf-php.html#deprecation-108345-1774126701)). If your extension needs to be compatible with TYPO3 Classic mode, add the following to the [`composer.json`](ComposerJson.md#file-extension-composer-json) file in your extension: - Set the extension version in the `version` field. This version should match the version previously defined in `ext_emconf.php` and the released Git tag. - Declare any plain (non-TYPO3 extension) Composer package dependencies (rather than on other TYPO3 extensions which are specified under `require`) in `extra.typo3/cms.Package.providesPackages`. - If your extension does not have any Composer package dependencies, set `providesPackages` to an empty object. This avoids deprecation messages and declares future compatibility with TYPO3 Classic mode. See [Classic-mode compatible composer.json](https://docs.typo3.org/permalink/t3coreapi:ext-composer-json-classic-compatible@14.3)