[MacCatalyst] WebViewShouldLoadEncodedUrl flaky on macOS 26 Helix queue (TimeoutException)

[PureWeen]

Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1342063
Build error leg or test failing: Microsoft.Maui.DeviceTests.WebViewHandlerTests.WebViewShouldLoadEncodedUrl
Pull request: #34550

Error Message

Fill the error message using step by step known issues guidance.

{
  "ErrorMessage": "WebViewShouldLoadEncodedUrl",
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Description

WebViewHandlerTests.WebViewShouldLoadEncodedUrl is intermittently failing with System.TimeoutException on MacCatalyst device tests running on the osx.26.arm64.open Helix queue (macOS 26). The test never fails on osx.15.arm64.maui.open (macOS 15).

Failure Details

• Test: Microsoft.Maui.DeviceTests.WebViewHandlerTests.WebViewShouldLoadEncodedUrl
• Parameter: encodedUrl: "https://example.com/test/%3Cvalue%3E" (and potentially other URLs)
• Exception: System.TimeoutException : Arg_TimeoutException
• Platform: MacCatalyst only, osx.26.arm64.open Helix queue
• Runtimes affected: Both CoreCLR and Mono

Evidence Across Builds

Build	Branch	Runtime	Queue	Result
1338787	net11.0	Mono	osx.26	✅ Pass
1341610	net11.0	Mono	osx.26	✅ Pass
1341651	main	Mono	osx.26	❌ Fail
1341764	main	Mono	osx.26	✅ Pass
1342063	PR #34550	CoreCLR	osx.26	❌ Fail
1342063	PR #34550	Mono	osx.26	❌ Fail
1342063	PR #34550	Both	osx.15	✅ Pass

The test fails on both main and net11.0 merge PRs — it is not introduced by any specific change.

Root Cause Analysis

The test (source) makes real HTTP requests to external URLs (example.com, google.com) and waits with a 5-second timeout:

var navigationResult = await tcs.Task.WaitAsync(TimeSpan.FromSeconds(5));

On the macOS 26 Helix queue (osx.26.arm64.open), network latency or DNS resolution occasionally exceeds 5 seconds, causing TimeoutException. The macOS 15 queue (osx.15.arm64.maui.open) appears to have more consistent network performance.

Suggested Fixes

1. Increase timeout from 5s to 15–30s (simplest fix)
2. Use local/mock URLs instead of external sites to eliminate network dependency entirely
3. Add retry logic for transient network failures

Option 2 is the most robust — device tests should not depend on external network availability.

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1342063
Error message validated: [WebViewShouldLoadEncodedUrl]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 3/20/2026 9:21:12 PM UTC

Report

Build	Definition	Test	Pull Request
1406001	dotnet/maui	WebView loads non-Western character encoded URLs correctly
1388499	dotnet/maui	WebView loads non-Western character encoded URLs correctly
1386468	dotnet/maui	Microsoft.Maui.Core.DeviceTests.WorkItemExecution
2954320	dotnet-maui	WebView loads non-Western character encoded URLs correctly
1383544	dotnet/maui	WebView loads non-Western character encoded URLs correctly

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
0	1	5