The full RealityKit Object Capture stack fails device-specifically on the iPhone 17 Pro family (iPhone18,1 / iPhone18,2) under iOS 26.x. Both the live and offline paths break. The same code and images work on iPhone 12 Pro (iPhone13,3) at the same iOS version. Both ObjectCaptureSession.isSupported and PhotogrammetrySession.isSupported return true on the 17 Pro, so there's no API signal that the operation will fail — it only fails at runtime on real hardware.
Defect 1 — ObjectCaptureSession.Error.sensorFailed
A guided capture session fails. On iOS 26.4.2 it fails at scan start. On iOS 26.5 it reaches .capturing and renders the live session for several seconds, but auto-capture never fires; attempting a manual capture then fails. The Swift enum (.sensorFailed) hides the cause; the underlying framework log is:
<<<< FigXPCUtilities >>>> signalled err=-17281 at <>:308
<<<< FigCaptureSourceRemote >>>> Fig assert: "err == 0 " at bail (FigCaptureSourceRemote.m:569) - (err=-17281)
ObjectCaptureSession.takeStillImageCapture(isAutoCapture:): Failed to capture high resolution frame!
ARSession <0x…>: did fail with error: Error Domain=com.apple.arkit.error Code=102 "Sensor failure."
UserInfo={NSUnderlyingError=0x… {Error Domain=AVFoundationErrorDomain Code=-11819 "Cannot complete action"
UserInfo={NSLocalizedRecoverySuggestion=Try again later.}}
NSLocalizedFailureReason=The sensor did not provide the required data.}
Capturing failed with error: objectCaptureSessionError(CoreOC.ObjectCaptureSession.Error.sensorFailed)
A second, uncatchable variant aborts instead of returning the error:
Abort: …/AppleCVHWA/library/VIO/HWFeatureDetection/src/HwGeneralProcessingAPI.cpp:711
: Original error reported by request utility function: kVisionHWAReturnGeneralProcessingFailed
Appears to be mediaserverd resetting (−11819) underneath the live AVCaptureSession, tearing it out from under ARKit (ARError 102). Configuration-independent: tested with isOverCaptureEnabled = false and the identical chain still occurs.
Defect 2 — PhotogrammetrySession reconstruction (cv3dapi 4004)
Folder-mode reconstruction starts but fails after a few seconds; SfM builds no pose map:
ERROR cv3dapi.pg: Internal error codes (1): 4004 // "No SfM map found"
WARN cv3dapi.pg: Internal warning codes (2): 2502 3502
Output error with code = -15
requestError: CoreOC.PhotogrammetrySession.Error.processError
The input is just a folder of images handed to PhotogrammetrySession in folder mode — no other configuration. The same folder reconstructs fine on the 12 Pro.
Affected config
- Failing: iPhone 17 Pro (
iPhone18,1), 17 Pro Max (iPhone18,2), iOS 26.4.2 and 26.5 - Working (same code/OS): iPhone 12 Pro (
iPhone13,3)
Open question
Does a 17-Pro image set fail PhotogrammetrySession everywhere, or only on the 17 Pro? Fails everywhere → 17 Pro images / HEIC metadata confuse SfM. Works elsewhere → the on-device reconstruction engine itself is the defect. Sample image set + sysdiagnose available on request.
References
cv3dapi 4004 = "No SfM map found" (683300) · -15/processError wrapper (794169) · iOS 26 Object Capture regression (810496) · 17 Pro Max sensorFailed (827216)