Apple's SDK cutoff takes effect April 28, 2026. After that date, App Store Connect will reject binaries built with older SDKs, including builds targeting iOS 25 and earlier. The requirement extends to both apps and games, and applies to net-new submissions as well as updates to existing titles. Teams that still depend on deprecated APIs or Objective-C toolchains that have not been adapted for iOS 26 need to finish migration before the cutoff. Practical prep work: update Xcode to 26.4.1, re-run TestFlight validation on the iOS 26 SDK, and confirm third-party SDKs have shipped compatible releases.