[BUG] Claude Desktop persistent blank/white screen on Windows — Cowork unusable, multiple reinstalls have no effect

Found 3 possible duplicate issues:

1. https://github.com/anthropics/claude-code/issues/50875
2. https://github.com/anthropics/claude-code/issues/44558
3. https://github.com/anthropics/claude-code/issues/28304

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🤖 Generated with Claude Code

+1

This gets weird. I erased every instance of Claude in the Task manager. Cleared the cache for all time. Web Claude disappeared. I shut down the computer and had a beer. Now I turned it back on, went to Claude.ai and downloaded Claude Desktop. When I installed it Web Claude came back. Now when I click the black icon in the system tray I get the dialogue bubble but no screen. And there are 10 instances of Claude in the task manager. How long will it take Anthropic to get a fix? I am okay with continuing to work with Web Claude, but I really want to work with cowork plugins.
This is the fifth time I have downloaded and installed Claude Desktop
In summary:
Missing %LocalAppData%\AnthropicClaude folder
10 Claude processes in Task Manager but no window rendering
%AppData%\Claude exists but only contains claude-code
Windows version 11 running on a Geekom Air12 Intel processors
A full uninstall, cache clear, reboot, and reinstall didn't resolve it

Exactly the same for me. I have previously had Claude working fine but recent updates and bugs brought this issue to my attention so I tried to reinstall from scratch with no other programs ( apart from background apps running and have had the same experience as everyone else. tried multiple ureinstalls, cleared cache etc

If you are using a custom DNS, check to make sure it isn't blocking Claude. I had the same issue, removed my custom DNS and the issue stopped for desktop version and the browser version.

+1

Same here. Definitely not running a custom DNS. Glad I'm paying Anthropic $$$ for this.

I am experiencing the exact same issue on Windows 11. Blank white screen, Cowork unusable, no app data folders created, multiple reinstalls have not helped. I am a paying customer and have been unable to access Cowork for multiple days. Please fix this urgently.

Same Issue — Windows MSIX, White Screen on Every Launch (ERR_QUIC_PROTOCOL_ERROR)

Environment

• OS: Windows (x64)
• App Version: Claude Desktop 1.12603.1 (MSIX)
• Install Source: https://claude.com/download (official)
• Package: Claude_pzs8sxrjxfjjc
• Developer Mode: ON (AllowDevelopmentWithoutDevLicense = 1)

Symptoms

• White/blank screen immediately on every launch
• App window renders but content area is entirely white
• No user interaction possible
• Reproduced on a second PC with a different network environment
• Web version (claude.ai) works normally in browser

Root Cause (from logs)

Analysis of main.log identified the following error sequence:

2026-06-12 15:56:05 [info] Failed to load URL: https://claude.ai/
  { errorCode: -356, errorDescription: 'ERR_QUIC_PROTOCOL_ERROR' }
2026-06-12 15:56:05 [info] Error page detected: { href: 'chrome-error://chromewebdata/' }
2026-06-12 15:56:05 [info] Redirecting to claude.ai
2026-06-12 15:56:08 [warn] [LocalSessionManager] Cannot initialize sessions: accountId=null, orgId=null
2026-06-12 15:56:08 [info] [account] Account details not yet available, waiting for IPC...
2026-06-12 15:56:49 [warn] [buddy-ble] mainView not ready: Timed out waiting for mainView to become ready

The Electron/Chromium engine fails to load claude.ai via QUIC (HTTP/3 over UDP 443), which cascades into account session failure and a permanent white screen timeout.

Troubleshooting attempted (all failed)

| # | Action | Result |
|---|--------|--------|
| 1 | GPU/Shader cache deletion | No improvement |
| 2 | Full uninstall + residual folder removal (%LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc) | No improvement |
| 3 | Clean reinstall from official installer | No improvement |
| 4 | Developer Mode verification | Confirmed ON |
| 5 | MSIX package repair | No improvement |
| 6 | Full LocalCache deletion | No improvement |
| 7 | QUIC disabled via registry (HKLM/HKCU QuicAllowed=0) | No improvement |
| 8 | QUIC disabled via Chromium policy | No improvement |
| 9 | electron-flags.cfg with --disable-quic | Ignored by MSIX build |
| 10 | UDP 443 firewall block for Claude.exe | No improvement |
| 11 | VPN/Proxy/Antivirus ruled out | Not the cause |
| 12 | TCP connectivity verified | TcpTestSucceeded: True for claude.ai:443 |
| 13 | Reproduced on second PC, different network | Confirms app-side bug |

Key finding: electron-flags.cfg (with --disable-quic) is not respected by the MSIX package distribution, making client-side QUIC workarounds ineffective.

Requested fix

• Automatic fallback from QUIC to TLS/TCP when ERR_QUIC_PROTOCOL_ERROR is encountered
• User-visible error/retry instead of silent white screen on page load failure
• Investigate why electron-flags.cfg is not respected in the MSIX build

Cowork is completely inaccessible as a result. Happy to provide additional logs if helpful.

Update: Issue Resolved (2026-06-23)

The app started working again today without any changes on my end — the login screen appeared normally on launch.

This suggests the fix was either a server-side change by Anthropic or an automatic app update. Leaving this here in case it helps others experiencing the same ERR_QUIC_PROTOCOL_ERROR white screen issue.

Additional info: OS is Windows Home edition.

Following this, having the same issue and nothing works... Thanks.

Same issue.

Managed to get Claude functional again by doing a full reinstall/repair from the Windows Add/Remove programs prompt. This deleted all my cowork projects and chat history.

I was able to recover everything from a Windows backup, but that also brough back the blank screen issue, and I've been completely unable to use Claude since.

Same problem. It happened after I updated my Nvidia drivers.

I used Claude in powershell mode to fix the problem.

Try the following:

1. Antivirus/Security — Check if you have Kaspersky, ESET, Norton, or similar. Many block QUIC. Disable it temporarily and test.

1. Router — Access the router's control panel and check if UDP on port 443 is blocked (some routers have "QoS" or "SPI Firewall" that blocks QUIC).

1. VPN — If you use a VPN, disable it and test.

1. Force HTTP/2 — In the Windows Firewall, it intentionally blocks UDP 443 to force Electron to drop to TCP/HTTP2.

Hope this helps.

Platform: Claude Desktop (Windows)

Claude Desktop Version: Latest

Operating System: Windows 11 Home 64-bit (Build 26200)

GPU: NVIDIA GeForce RTX 5070 (Driver 32.0.16.1047, dated 5/19/2026)

Monitor setup: Desktop PC (stationary) with external monitor
Problem:

Claude Desktop opens to a completely blank/white screen on every launch. The window frame appears with minimize/maximize/close buttons, but no content ever renders.
What I tried:

Killed all Claude processes via Task Manager and relaunched — no effect
Deleted %APPDATA%\Claude cache folders (Cache, Code Cache, GPUCache) — no effect
Added --disable-gpu launch flag — no effect
Full clean reinstall (uninstalled, deleted all AppData folders, rebooted, reinstalled) — no effect
Note: %LocalAppData%\AnthropicClaude folder was not created after reinstall, suggesting the app is failing to initialise properly

Expected behaviour:

App should launch and display the UI normally.

I hit a related Windows Desktop failure mode where the browser could open https://claude.ai, but Claude Desktop either failed to render / could not connect through the same proxy path.

I published an unofficial workaround here:

https://github.com/king-sheol/claude-desktop-windows-proxy-launcher

Latest release ZIP:
https://github.com/king-sheol/claude-desktop-windows-proxy-launcher/releases/latest

Scope / caveats:

• Unofficial, not affiliated with Anthropic.
• Does not modify, patch, decompile, or redistribute Anthropic software.
• Does not delete Claude data, projects, sessions, plugins, or settings.
• Does not replace the official Claude shortcut.
• It is not a universal Cowork VM networking fix.

What it does:

• Launches the existing Claude.exe with explicit Chromium/Electron flags such as --proxy-server, --disable-quic, and GPU-workaround flags.
• Also sets proxy environment variables for child processes.
• Searches for both MSIX/AppX and Win32/Squirrel install locations.
• Includes a dry-run mode and an optional shortcut installer that creates a separate Claude Desktop Proxy Launcher shortcut.

This is most relevant for cases where claude.ai works in the browser, but the main Claude Desktop Electron UI is blank, white-screened, or shows "Could not connect to Claude". It may also help users whose MSIX build ignores electron-flags.cfg, since the flags are passed at process launch instead.

Again, this is a workaround, not a replacement for an upstream fix. Ideally Claude Desktop should expose supported proxy / network settings and handle QUIC/proxy failures with a visible retry/error path instead of a permanent blank screen.

I realized that my computer set time was out of sync, changed it from manual to auto, and reopened claude and it fixed the issue.