Announcement: Xcode15 Deprecation in Semaphore

Semaphore is ending support for MacOS Xcode15 build environments to maintain platform security, reliability, and maintainability. Users are encouraged to switch to Xcode26, as Xcode16 will also be deprecated by September 2026. The deprecation process for Xcode15 involves phased brownout periods starting in June 2026, where jobs configured for Xcode15 will temporarily fail to start to help users identify and update any remaining dependencies. The first brownout will last for 15 minutes, increasing to 60 minutes during the second, and two hours in the third, culminating in the complete removal of Xcode15 from July 6, 2026. Users should update their pipelines to a supported Xcode version, either Xcode26 or, if necessary, Xcode16, while ensuring all dependencies and scripts are compatible. Semaphore provides support and documentation to assist users in the transition, urging completion of migration before the first brownout period.