:_mod-docs-content-type: REFERENCE [id="ref_rn-qdocs-1330-legacy-config-classes-removed"] = Configuration: Legacy config classes removed In the current release, Quarkus removes support for legacy configuration classes. Applications that rely on extensions, including custom extensions, built on legacy configuration classes, fail to build. Update affected extensions to versions that use `@io.smallrye.config.ConfigMapping`, or migrate custom extensions accordingly. For example, replace the compatibility class `GlobalDevServicesConfig` with `DevServicesConfig`. For more information, see: * the Quarkus link: https://github.com/quarkusio/quarkus/wiki/Migration-Guide-3.26#legacy-config-classes-support-is-gone [Migration guide 3.26: legacy config classes support is gone] * the Quarkus link: https://quarkus.io/blog/legacy-config-classes-sunsetting/ [Sunsetting legacy config classes] // https://issues.redhat.com/browse/QDOCS-1330 // SME: Guillaume Smet // Core // Breaking change // include::rn/ref_rn-qdocs-1330-legacy-config-classes-removed.adoc[leveloffset=+2]