Area: UIKit / Files / Document Picker (or Safari / WebKit if that category fits better — root UI is Files)
Summary
On iPhone Air running iOS 26.4 (also reproduced on iPhone Air Simulator with iOS 26.5), presenting the system file picker freezes / becomes unresponsive.
The same build and the same iOS major version work correctly on iPhone 17 Pro.
This happens for BOTH:
- WKWebView default file upload panel triggered by <input type="file">
- Native UIDocumentPickerViewController presented from UIKit
So this is not specific to WKWebView’s WKFileUploadPanel alone — it appears to be a Files / File Provider UI issue on iPhone Air.
Environments
FAILS:
- Device: iPhone Air (model identifier iPhone18,4)
- OS: iOS 26.4 (production customer report)
- Also: iPhone Air Simulator, iOS 26.5 — same freeze
WORKS:
- Device: iPhone 17 Pro (simulator and comparison testing)
- OS: same iOS 26.x line
- Also: iOS 18.4 Simulator — file picker works
Steps to Reproduce
A) Via WKWebView (HTML file input)
- Open an app that hosts a WKWebView loading a page with <input type="file" multiple>
- Tap the control that triggers file selection
- System Files UI appears (often on “Recents” / 最近项目)
B) Via native UIDocumentPickerViewController
- Present UIDocumentPickerViewController(forOpeningContentTypes:asCopy: true) for image/pdf types
- allowsMultipleSelection = true
- modalPresentationStyle = .fullScreen (also tried default sheet)
Actual Results
- UI opens but hangs / freezes
- Typical UI state: empty white content area
- Tabs may still show Recents / Shared / Browse
- On Browse → “On My iPhone”, content area stays blank and UI is unresponsive
- Cancel / switching tabs often does not work
- User cannot select a file; must force-quit the app
Expected Results
Document picker remains interactive; user can browse and select files (as on iPhone 17 Pro with the same OS).
Comparison
| iPhone Air + iOS 26.4 (device) | Freeze |
| iPhone Air Simulator + iOS 26.5 | Freeze |
| iPhone 17 Pro + iOS 26.x | OK |
| Simulator iOS 18.4 | OK |
| Photo library / UIImagePicker | OK on Air |
Photo/camera pickers work on iPhone Air. Only the Files / document picker path fails.
Impact
Production customers on iPhone Air + iOS 26.4 cannot upload documents (PDF/files) in our hybrid insurance app (WKWebView). Image upload via photo library still works. This blocks claims / document upload flows for Air users.
Notes / attempts
- Not fixed by switching from WKWebView <input type="file"> to UIDocumentPickerViewController
- not fixed by asCopy: true
- not fixed by fullScreen presentation
- not fixed by setting / clearing directoryURL
- App-side workarounds (camera / photo library only) avoid Files UI but do not restore true file picking
Please investigate Files / Recents / On My iPhone enumeration hang specific to iPhone Air on iOS 26.4+.
Attachments to add
- Screen recording: freeze on iPhone Air
- Screen recording: same steps on iPhone 17 Pro (works)
- Screenshots of frozen Recents / Browse empty state
- sysdiagnose from iPhone Air if possible (Settings → Privacy & Security → Analytics, or instruct via Feedback Assistant)
