Foundation Model tool calling giving system error in iOS27 beta 5

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Created 17h

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After updating my iOS and xcode to latest iOS 27 beta5 and xcode 27 beta5 all the system language model session calls with tool calls inclusion throwing Unrecognized system-instruction prefix ID: com.apple.fm_api.tool_calls_override error.

The same code was working perfectly in iOS27 beta 4. Even the apple sample project OrigamiCraftingADynamicTutorialForAppleIntelligence failing with the same error when tool calls invoked. Anybody else facing similar issue or any workaround for this issue?

sample code: struct GetRecordNotesTool: Tool { let name = "getRecordNotes" let description = "Fetches internal notes and returns Note_Title and Note_Content for up to 10 notes."

@Generable
struct Arguments {
    @Guide(description: "The API name of the module, e.g. Companies or Contacts")
    var module_api_name: String

    @Guide(description: "The unique record ID to fetch notes for")
    var record_id: String
}

func call(arguments: Arguments) async throws -> String {
  return "Fetched content"
}

}

Answer 1

Apple Designer OP

Apple

2h

Thanks for reporting!

This error (which is possibly a bug) indicates that while you updated iOS and Xcode, the system model's assets either weren't finished downloading or weren't finished installing.

A couple questions to diagnose what might have gone wrong:

If you try again today, are you still getting this error? It might have resolved on its own if it was a pending update.
If the error is still there: can you kindly share the result of running SystemLanguageModel.default.availability? That should give a clue about the model's state. Then, I'd suggest restarting your iOS device and waiting 5-10 minutes to see if the pending update resolves on its own.