Claude Not Working? How to Fix Crashes and Errors

Claude not working usually surfaces in one of three ways: a sudden stream termination mid-response (“This isn’t working right now”), the Windows desktop app failing to launch with a silent background crash, or an interface stuck on an indefinite loading spinner during heavy document parsing.

Claude delivers reliable conversational intelligence across web, mobile, and native desktop clients, but the interaction between local browser cache, the Windows MSIX application sandbox, and Model Context Protocol (MCP) server timeouts can trigger distinct application stalls, each requiring a different fix.

Why Claude Fails: The Core Root Causes

1. Windows MSIX Container Faults and Embedded Renderer Stalls

The Windows desktop client runs inside a sandboxed MSIX package rather than a traditional standalone installer, isolating its files and registry entries from the rest of the system. When the internal Chromium-based webview suffers a GPU rendering crash — most often triggered during heavy Artifact rendering with complex interactive components — Windows flags the package with a Status: Modified, NeedsRemediation fault, which blocks subsequent launch attempts entirely until the package registry state is repaired.

This is why a simple relaunch attempt after this kind of crash typically fails silently: the operating system itself is refusing to start a package it has flagged as inconsistent, rather than the application encountering a fresh error each time.

2. Streaming WebSocket Disconnects and Edge Throttling

Long-form reasoning responses are delivered as a continuous token stream over a persistent WebSocket connection rather than a single static request. When a corporate firewall, a VPN exit node, or a high-latency ISP route drops the connection’s keep-alive packets mid-generation, the session terminates abruptly with a generic “An error occurred while generating” message instead of pausing and quietly reconnecting.

This distinction matters for diagnosis: a slow connection still delivers data, just with lag, while a dropped keep-alive severs the stream outright, which is why the fix is a fresh session rather than simply waiting longer.

3. Model Context Protocol (MCP) Daemon Timeouts

On the desktop client specifically, locally configured MCP servers — connectors to a local database, a file system, or a development tool — run as independent processes launched during application startup. When one of these local servers crashes, hangs during its own startup sequence, or contains malformed JSON syntax in claude_desktop_config.json, the entire desktop client shell can freeze during initialization, since the client waits on that server’s response before finishing its own launch sequence.

This is a desktop-specific failure mode with no equivalent on web or mobile, since neither of those clients loads local MCP configuration at all.

Step-by-Step Fixes: What to Do When Claude Not Working

Fix 1: Purging Browser Session Cache and Resetting Cloudflare Cookies

1. Open browser settings and navigate to Settings → Privacy and Security → Clear Browsing Data.
2. Under the Advanced tab, select a time range of All Time, verify that Cookies and other site data and Cached images and files are both checked, and click Clear Data.
3. Open an Incognito/Private window using Ctrl + Shift + N (Chrome/Edge) or Ctrl + Shift + P (Firefox), navigate to claude.ai, and perform a hard cache bypass via Ctrl + F5 before signing back in.

Fix 2: Repairing and Re-Registering the Windows MSIX Desktop Package

1. Navigate to Start → Settings → Apps → Installed Apps. Locate Claude, click the three horizontal dots, select Advanced options, and click Repair.
2. If the app still fails to open, return to the same screen and click Reset to wipe local container state without removing the binary itself.
3. For stubborn package corruption, open Windows PowerShell as Administrator and run the following command to re-register the app container:

Get-AppxPackage -Name Claude | Reset-AppxPackage

Fix 3: Clearing Local macOS Application Support Cache and GPU Logs

1. Force quit the frozen application by pressing Cmd + Option + Escape, selecting Claude, and clicking Force Quit.
2. Open Finder, press Cmd + Shift + G, paste the path ~/Library/Application Support/Claude, and press Enter.
3. Move the Cache, GPUCache, and Session Storage directories to the Trash, then relaunch the desktop app.

Fix 4: Debugging and Resetting the Model Context Protocol (MCP) Config

Step-by-Step Instructions

1. Open the local configuration file:
   • Windows: %APPDATA%\Claude\claude_desktop_config.json
   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
2. Validate the JSON syntax in a text editor, checking specifically for trailing commas or unescaped backslashes, both common causes of a silent parse failure.
3. If crashes persist on launch, temporarily rename the file to claude_desktop_config.json.bak and restart Claude to determine whether a third-party MCP server daemon was causing the startup hang.

Submitting an Actionable Ticket to Anthropic Support

If none of the fixes above resolve the issue, visit support.anthropic.com or open the in-app support widget (Help Icon → Contact Support). Include the account email, the exact operating system build, browser version, the timestamp of the failure, and a console log export captured via Developer Tools (F12 → Console) — this level of detail consistently speeds up ticket triage.

Once access is restored, it’s worth revisiting daily habits that reduce how often these errors recur — this complete guide on how to use Claude effectively covers the account and workspace practices that prevent several of these issues from resurfacing.