qrcp receive mode shows blank white page — previously worked on same iOS version

[eiger3970]

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Environment

• Server: Raspberry Pi 5

• OS: Raspberry Pi OS (bookworm)

• qrcp version: (to be filled)

• Firewall: ufw active, port manually allowed

• Client: iPhone 11, iOS 26.1

• Browsers tested: Firefox, Safari, Chrome

Expected Behavior

Scan QR code → upload interface with file selection buttons appears → user uploads photos from iPhone to Pi.

Actual Behavior

Browser loads blank white page (no upload buttons, no UI elements). Connection succeeds (not a timeout), but interface fails to render.

Key Distinction

This worked previously on the exact same iOS 26.1 version. Something changed on the server side or network configuration, not the iOS version.

What Changed (Unknown)

Possible causes being investigated:

• Raspberry Pi IP address changed

• Background qrcp process left running (port conflict)

• Firewall rule not applying correctly despite appearing in ufw status

• Network interface binding issue

Troubleshooting Attempted

Attempt	Result
Verify firewall allows port 43283	✅ Rule #5 shows 43283/tcp ALLOW IN
Check for port conflicts	✅ 43283 not in use by other services
Kill stale qrcp processes	✅ Fresh instance running
Test different browsers on iPhone	❌ All show blank white page
Use --webkit flag	❌ No change
Force --interface wlan0	❌ No change
Test different port (43285)	❌ No change
qrcp send mode (Pi → phone)	✅ Works correctly
python3 -m http.server	✅ Directory listing renders fine
Check if Pi's IP changed	IP confirmed as 172.20.10.2 (matches URL)

Network Configuration

• Server IP: 172.20.10.2

• Connection: iPhone Personal Hotspot (both devices on same network)

• Firewall: active, port open

Remaining Hypotheses

1. Stale browser cache on iPhone — old JavaScript being served?

2. qrcp version changed (unintentional update)

3. Missing MIME type — HTML serving but CSS/JS blocked

4. WebSocket handshake failing silently

Next Debugging Steps Needed

• Clear iPhone browser cache/cookies and retry

• Check qrcp --version (compare to previously working version)

• View browser console logs (requires macOS + Safari Web Inspector)

• Test from a different client device (another phone/computer)

• Check if HTML body contains hidden elements vs. truly empty

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[claudiodangelis]

Thanks for the detailed report, nothing changed in the last few months, I'll have an eye on it in a couple of days.

C

[claudiodangelis]

When was the last time it was working?

[eiger3970]

Good question...perhaps 4 weeks ago around mid March 2026?
Browser preferred that I typically use is Firefox 147.5 (67839) on iPhone 11 iOS 26.1.
If I think of any changes I made at that time, I'll update the post.