OpenClaw Companion (Windows) crashes within 6-90s of startup - WinUI 3 ArrangeOverride throws E_INVALIDARG

Summary

Companion (v2026.9.3, Windows 11 24H2) reliably crashes 6–90 seconds after startup, every launch. The crash happens while the native XAML chat view is rendering the gateway-pushed wizard/startup data. It is an app-side WinUI 3 layout bug, not an environment problem. Setting "UseLegacyWebChat": true in %APPDATA%\OpenClawTray\settings.json (chat falls back to the legacy Web rendering path) fully avoids the crash — verified stable for 180s+ across multiple restarts.

Environment

Symptoms

• App exits 6–90s after launch, every time; window may flash and disappear.
• Windows Event Log (Application Error): exception code 0xc000027b (STATUS_STOWED_EXCEPTION), faulting module Microsoft.UI.Xaml.dll.
• App crash.log: System.ArgumentException: 参数错误。 with the stack pinned to IFrameworkElementOverrides.ArrangeOverride (see below).
• App log shows the crash happens ~137ms after the gateway handshake completes and the chat.history wizard response (~84KB, kind=Object) arrives — i.e., exactly while the main chat view is rendering.
• Unrelated to gateway connectivity: crashing also occurs with the gateway unreachable (ws://127.0.0.1:19999 dead).

Crash stack (crash.log)

System.ArgumentException: 参数错误。

   at WinRT.ExceptionHelpers.<ThrowExceptionForHR>g__Throw|38_0(Int32 hr)
   at WinRT.ExceptionHelpers.ThrowExceptionForHR(Int32 hr)
   at ABI.Microsoft.UI.Xaml.IFrameworkElementOverridesMethods.ArrangeOverride(IObjectReference _obj, Size finalSize)
   at Microsoft.UI.Xaml.FrameworkElement.ArrangeOverride(Size finalSize)
   at Microsoft.UI.Xaml.FrameworkElement.Microsoft.UI.Xaml.IFrameworkElementOverrides.ArrangeOverride(Size finalSize)
   at ABI.Microsoft.UI.Xaml.IFrameworkElementOverrides.Do_Abi_ArrangeOverride_1(IntPtr thisPtr, Size finalSize, Size* result)

App log (137ms before crash):

[13:49:05.126] [GatewayClient] Sending frame: chat.history
[13:49:05.144] Wizard response payload kind=Object len=84585
[13:49:05.283] [ERROR] CRASH UnhandledException: System.ArgumentException: 参数错误。

Root cause analysis

The crash originates in the native layout implementation of Microsoft.UI.Xaml.dll: the managed layer calls IFrameworkElementOverrides.ArrangeOverride, and the native side returns E_INVALIDARG (0x80070057). In WinUI 3 this is typical when a chat message / wizard payload with a specific structure (nested cards, Markdown, tool-call blocks) produces an invalid size during measure/arrange.

Evidence chain:

1. Crash timing strictly matches the wizard response rendering (137ms window).
2. With the gateway disconnected the app still crashes — the main chat view requests and renders that data regardless, so disconnecting cannot bypass it.
3. "UseLegacyWebChat": true switches the chat to the WebView path, which never touches the native XAML chat controls — crashes stop. This inversely confirms the native chat view layout path as the culprit.
4. Scale 150%, third-party injections, and system component state were all ruled out one by one (Oray disabled, Nahimic stopped, sfc /scannow clean, DPI compat flags, reinstall, NodeCanvasEnabled/NodeScreenEnabled=false).

Workaround (verified)

Edit %APPDATA%\OpenClawTray\settings.json:

{
  "UseLegacyWebChat": true,
  "AppTheme": "Light"
}

Result: 0 crashes across multiple restarts, 180s+ continuous uptime, all features (chat/settings/notifications/hotkeys) functional. AppTheme: Dark also crashes in the same environment, so the theme change alone is not sufficient — the key switch is UseLegacyWebChat.

Reproduction steps

1. Windows 11 24H2 + Companion 2026.9.3 + Gateway 2026.9.4 (node26).
2. Complete pairing, then start Companion and wait for the main chat view to load the wizard startup data. Reproduces consistently at 150% display scale (appears deterministic).

Suggested fix direction

• Review the rendering path of sessions.messages / chat.history wizard payloads (kind=Object, ~84KB) in the native chat message-list control; focus on layout measurement of wizard card structures (nested cards / Markdown / tool-call blocks).
• Regression-check the Dark theme path (AppTheme=Dark), which crashes in the same environment.
• Consider auto-falling back to UseLegacyWebChat for affected users, or routing wizard startup data to a Web-chat-only channel.

Additional material

A full 7-page troubleshooting report (Chinese) with all logs, timeline and verification data is available on request — happy to share it here if maintainers want the complete evidence.

Reproduce on Windows 11 24H2 with Companion 2026.9.3, 150% scale, and the native chat path enabled, then trace rendering after the chat.history wizard response arrives. Focus on the native chat message-list layout for nested cards, Markdown, and tool-call blocks, including the Dark theme path. Done means the startup data renders without the ArrangeOverride E_INVALIDARG crash, while UseLegacyWebChat remains a verified workaround.