I'm trying to run the Instrument "Animation Hitches", but it fails immediately after starting on the iPhone. This happens on multiple projects, including a brand new project.

I get the following errors:

Timestamp	Message
(Before Run Started)	Unexpected failure: Couriers have returned unexpectedly.
(Before Run Started)	Failed to start the recording: Failed starting ktrace session.

I'm trying to run the Instrument "Animation Hitches", but it fails immediately after starting on the iPhone. This happens on multiple projects, including a brand new project.

I get the following errors:

Timestamp	Message
(Before Run Started)	Unexpected failure: Couriers have returned unexpectedly.
(Before Run Started)	Failed to start the recording: Failed starting ktrace session.

The issue also happens with the instruments App Launch, but not with any other that I tested.

Is this a bug?

Using Xcode Version 16.1, Mac Mini M1 Sequoia 15.1. Running project on iPhone 14 Pro iOS 18.1.

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Share Improve this question Follow edited Nov 19, 2024 at 5:29 Rob 439k7474 gold badges841841 silver badges1.1k1.1k bronze badges asked Nov 19, 2024 at 2:29 Cécile LebleuCécile Lebleu 19644 silver badges1717 bronze badges 0

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1 Answer 1

Sorted by: Reset to default 1

The problem would appear to be using “Recording mode” of “Deferred” when profiling on a physical iOS device, regardless of which Instruments template you choose. If you change the recording mode to “Capture last n seconds” (or, where available, “Immediate”), this problem does not manifest itself.

This problem jumps out at you when using “Animation hitches” template because that template does not accept a recording mode of “Immediate” and defaults to “Deferred” mode. But if you pick a different template, and manually change its recording mode to “Deferred”, that will also manifest the same problem.

This seems worthy of a bug report.