Production fixes — field notes.

Errors I’ve debugged on real engagements. Each page is one error, one root cause, the fix paths ranked by frequency, and the edge cases that bit me. If you’d rather hand the problem off, I take on short B2B contracts.

#app-developmentExpo: "No code signing certificates are available to use" — fixWhy EAS / `npx expo run:ios` reports "No code signing certificates are available to use" and the exact steps that resolve it on local builds and CI.
#app-development"Embedded binary is not signed with the same certificate as the parent app" — fixWhy iOS rejects an app whose extension, framework, or watchOS app is signed by a different identity than the host — and the safe ways to make signatures match.
#app-development"Xcode failed to verify code signature" — fixWhy Xcode refuses to launch an app on device with "failed to verify code signature" and the four root causes ranked by frequency, with a fix for each.
#app-developmentEXC_CRASH (SIGKILL · Code Signature Invalid) — fixWhy iOS terminates your app at launch with EXC_CRASH SIGKILL and a code-signature-invalid termination reason — and the order to investigate.
#app-development"iPhone Distribution certificate is not trusted" — fixWhy Keychain Access flags your iPhone Distribution certificate as not trusted and the right way to repair the trust chain instead of overriding it.