native-crash-diagnostics

name

native-crash-diagnostics

description

Diagnose Yagu NATIVE fail-fast crashes that bypass managed exception logging — 0xc000027b / 0xc0000005 / StackHash in Microsoft.UI.Xaml.dll (WinUI) or an access violation / 0xc0000409 in the Rust yagu_core.dll. Use when: Yagu crashed, why did Yagu crash, Yagu crash diagnostics, root cause of a Yagu crash, native crash, access violation, 0xc000027b, 0xc0000005, 0xc0000409, StackHash, Microsoft.UI.Xaml crash, preview/editor crash, match-nav crash, no managed exception was logged, WER LocalDumps, crash dump.

Yagu Native Crash Diagnostics

Yagu's worst crashes are native fail-fasts, not managed exceptions: a WinUI fail-fast in Microsoft.UI.Xaml.dll (usually 0xc000027b, sometimes reported as StackHash) or a fault in the Rust yagu_core.dll (access violation 0xc0000005, or a Rust panic = "abort" that exits as 0xc0000409). These do NOT flow through .NET's UnhandledException, so App.xaml.cs never logs them, %APPDATA%\Yagu\yagu-crash.log stays empty, and a managed try/catch (Exception) around XAML geometry calls (e.g. TransformToVisual / GetCharacterRect in MainWindow.MatchNav.cs) does not catch them. Diagnose from Windows Error Reporting plus the verbose app log — never expect a managed stack.

Step 1 — Ensure crash dumps are captured

Debug builds of Yagu.csproj run this automatically, but to configure it by hand run the committed helper (HKCU, no elevation needed):

pwsh scripts/ensure-wer-localdumps.ps1 -DumpFolder C:\src\Yagu\TestResults\CrashDumps

It writes HKCU:\Software\Microsoft\Windows\Windows Error Reporting\LocalDumps\Yagu.exe with DumpType=2 (full), DumpCount=10, DumpFolder=C:\src\Yagu\TestResults\CrashDumps, and pre-creates the folder (WER silently skips capture if it is missing). Caveat: WER sometimes still routes a report through its own WER\Temp and produces no dump — do not assume a dump exists.

Step 2 — Build symbol-rich binaries

For a yagu_core.dll crash, or to get any usable native stack, build Debug with the Rust profiling profile so yagu_core.dll + yagu_core.pdb land beside Yagu.exe:

dotnet build src/Yagu/Yagu.csproj -c Debug -p:RustProfile=profiling -p:SkipYaguVersionIncrement=true

Then confirm both files exist under src/Yagu/bin/Debug/net10.0-windows10.0.19041.0/.

Step 3 — Read the evidence (WER + app log)

Query the Application log for the faulting module and exception code:

Get-WinEvent -FilterHashtable @{LogName='Application'; StartTime=(Get-Date).AddMinutes(-30)} |
  Where-Object { $_.ProviderName -in @('Application Error','Windows Error Reporting','.NET Runtime') -or
                 $_.Message -match 'Yagu|Microsoft\.UI\.Xaml|0xc000027b|0xc0000005|0xc0000409' } |
  Select-Object -First 20 TimeCreated, ProviderName, Id, LevelDisplayName, Message | Format-List

Then read %APPDATA%\Yagu\yagu.log — the last line before the process died is the strongest clue to which operation faulted. Enable verbose logging first via Settings (Log level = Verbose) or the installer /VERBOSELOG flag; a native fail-fast leaves the log truncated mid-operation (no Warning line, because it was not a managed error).

Step 4 — Match against known Yagu native-crash triggers

• Preview / editor 0xc000027b — a very large single-line file in the preview, then repeated word-wrap toggles + Select-All across the whole line + Find/Replace + scroll. The virtualized vendored TextControlBox selection over an unrendered slice fail-fasts. Reproduce with a big single-line file; see .github/instructions/preview-editor.instructions.md.
• Match-nav overlay — stale RichTextBlock geometry after result eviction/expansion. Forcing a final GetCharacterRect / ScrollPreviewToLine after the retry budget is exhausted fail-fasts. The fix pattern: do not re-touch geometry after retries exhaust — revalidate block/paragraph/run attachment and abandon stale overlay work.
• Rust panic = "abort" (0xc0000409) — a native panic in yagu_core.dll. Common causes: an mmap-threshold vs test-fixture mismatch, or a null-context callback. See .github/instructions/performance.instructions.md.

Step 5 — Prevent recurrences

Lightweight warning modals implemented as custom owned Windows have triggered these fail-fasts — prefer the in-window YaguDialog for simple warnings/prompts (see .github/instructions/modal-no-title-bar.instructions.md), and never re-enter stale XAML geometry after a layout change.