[Bug] Claude Desktop v1.1.4173 fails to show window on Windows 11 — downgrading to v1.1.4088 resolves the issue

Bug Report: Main window never appears after update to v1.1.4173

Summary

After the automatic update from v1.1.4088 → v1.1.4173, the Claude desktop app silently starts in the background but never shows any window. All claude.exe processes have MainWindowHandle = 0, meaning no window is ever created. Downgrading to v1.1.4088 restores normal behavior immediately.

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Environment

| Field | Value |
|---|---|
| OS | Windows 11 Home 10.0.26200 |
| CPU | Intel Core i7-14700K |
| RAM | 64 GB |
| Display | Single monitor (VG27AQ3A), 2560×1440 @ 141.25% DPI scaling, 60 Hz |
| Affected version | 1.1.4173 |
| Working version | 1.1.4088 |

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Steps to Reproduce

1. Let Claude auto-update to v1.1.4173 (via Squirrel)
2. After update, click the Claude desktop icon or shortcut
3. Claude appears to launch (processes appear in Task Manager) but no window is shown

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Observed Behavior

• 4 claude.exe processes are running (main + renderers), but all have MainWindowHandle = 0
• The first instance becomes the "main instance" correctly; subsequent launches are rejected with Not main instance, returning early from app ready
• The main process logs initialization steps up to GrowthBook/EventLogging, then goes completely silent — no window creation is ever logged
• The renderer process log (unknown-window.log) has zero entries from today, confirming the renderer is never invoked

Key log excerpt from main.log (every startup attempt, v1.1.4173):

2026-02-26 14:04:32 [error] Sentry caught: {
  type: 'Error',
  value: '[@formatjs/intl] An `id` must be provided to format a message...'
}
2026-02-26 14:04:33 [info] [growthbook] loaded 31 features
2026-02-26 14:04:33 [info] [EventLogging] Queuing event: desktop_windows_elevation_detected | metadata: {
  elevation_type: 'default',
  can_elevate: false,
  ...
}
2026-02-26 14:04:37 [info] Not main instance, returning early from app ready
2026-02-26 14:04:38 [info] [EventLogging] Flushing 2 events

(After this point — complete silence. No window is ever created or shown.)

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Attempted Workarounds (all failed for v1.1.4173)

| Workaround | Result |
|---|---|
| taskkill /F /IM claude.exe then relaunch | ❌ Still no window |
| Delete lockfile then relaunch | ❌ Still no window |
| Launch with --disable-gpu flag | ❌ Still no window |
| Delete GPUCache, DawnGraphiteCache, DawnWebGPUCache then relaunch | ❌ Still no window |

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Fix / Workaround That Works

Running the previous version binary directly:

C:\Users\<username>\AppData\Local\AnthropicClaude\app-1.1.4088\claude.exe

This immediately opens the Claude window normally (MainWindowHandle ≠ 0, title = "Claude").

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Suspicion

The [@formatjs/intl] An id must be provided to format a message error appears only in v1.1.4173 and not in any previous startup logs. This i18n error may be triggering an unhandled rejection or exception that silently prevents the BrowserWindow from ever being created in the main process, while still allowing the app to register itself as the "main instance" (blocking re-launches).

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Additional Notes

• Squirrel-Update.log confirms v1.1.4173 was installed cleanly on 2026-02-25
• No crash dumps exist in the Crashpad/reports/ directory — the process does not crash, it just hangs without showing a window
• The issue is 100% reproducible on this machine across multiple reboots and cleanup attempts