Claude Not Working? Fix Connection, Loading, and Response Errors

Overview

“Claude not working” covers a wide range of failures — blank screens on claude.ai, spinning loaders in the desktop app, connection timeouts in Claude Code, and HTTP errors from the API. The common thread is that Claude stops responding or refuses to start a conversation.

This guide walks through every surface where Claude can break: the web app, desktop app, mobile app, API, and CLI. Each section targets a different failure mode with concrete steps. Skip to the section that matches your setup.

Most failures fall into three buckets: Anthropic-side outages (you wait), session/auth problems (you re-login), or local environment issues (you fix your machine). The goal is to identify which bucket you’re in within two minutes.

Symptoms

What “not working” actually looks like depends on the surface you’re using. Here are the most common failure patterns:

claude.ai (web app): Page loads but the message input is unresponsive. Conversations show a perpetual loading spinner. You get a generic “Something went wrong” banner. Responses cut off mid-sentence and no retry button appears. The page is completely blank or stuck on a white screen after login.

Desktop app (macOS/Windows): App launches but shows a blank window. Conversations fail to sync. The app freezes or becomes unresponsive after sending a message.

Claude Code (CLI): Commands hang without output. You see Error: 529 Overloaded or Error: 401 Unauthorized. The CLI exits silently or throws network errors.

API: Requests return 500 Internal Server Error, 529 Overloaded, or 403 Forbidden. Timeouts on long responses. Sudden rate-limit errors (429) mid-session.

Why This Happens

Claude failures generally trace to one of these causes:

Server-side load or outages. Anthropic’s infrastructure may be under heavy demand or experiencing partial degradation. This is the most common cause during peak hours, and no local fix resolves it.

Stale sessions or expired tokens. Browser sessions expire. API keys get rotated or revoked. OAuth tokens in Claude Code hit their refresh window. The symptom is sudden auth failures after a period of normal use.

Browser interference. Ad blockers, privacy extensions (uBlock Origin, Privacy Badger), corporate proxies, and aggressive cookie policies can break WebSocket connections or block required API calls to Anthropic’s endpoints.

Network and firewall issues. VPNs, corporate firewalls, DNS filtering (Pi-hole, NextDNS), and restrictive network policies can silently drop connections to claude.ai or api.anthropic.com.

Local environment corruption. Stale caches, corrupted IndexedDB storage, or outdated desktop app versions cause rendering and state management failures.

Check Status, Account, and Basic Access

Start here every time. Open status.anthropic.com in a separate browser tab. Look at the current status of both “API” and “claude.ai” components. If either shows degraded performance or an active incident, that’s your answer.

Next, verify your account is in good standing:

• Free tier users: Check if you’ve hit your daily message limit. Claude will stop responding when the limit is reached, often without a clear error message. The interface may just show a spinner indefinitely.
• Pro/Team subscribers: Confirm your subscription is active. Go to Settings → Subscription in claude.ai. Expired payment methods cause silent failures.
• API users: Log into console.anthropic.com and check your usage dashboard. Verify that billing is active, your API key exists, and you haven’t exceeded your rate limit or spend cap.

Try loading https://claude.ai in a completely different browser. If it works there, the problem is browser-specific (jump to step 02). If it fails everywhere, the problem is account-level or server-side.

Fix Browser and Desktop App Sessions

Browser-side failures are the most common category for claude.ai users. Work through these in order:

Hard refresh. Press Ctrl + Shift + R (or ⌘ + Shift + R on Mac). This bypasses the browser cache and forces a full reload.

Clear site data. In Chrome: open DevTools (F12), go to Application → Storage, click “Clear site data” with claude.ai loaded. In Firefox: Settings → Privacy → Cookies → search claude.ai → Remove All. Then log back in.

Test in incognito/private mode. Open a private window and log into claude.ai. If it works there, a browser extension is the culprit. Common offenders: uBlock Origin (may block WebSocket connections), Grammarly (injects into text inputs), Dark Reader (can break dynamic UI rendering).

Disable extensions one by one. If incognito mode fixes it, re-enable extensions in your normal window one at a time until you find the conflict. Whitelist claude.ai in the offending extension rather than disabling it entirely.

Desktop app reset. The Claude desktop app uses an embedded browser engine (Electron). Stale cached data can cause blank screens or loading failures:

# macOS — clear desktop app cache
$ rm -rf ~/Library/Application\ Support/Claude/Cache
$ rm -rf ~/Library/Application\ Support/Claude/GPUCache

# Windows — clear desktop app cache
$ rd /s /q "%APPDATA%\Claude\Cache"
$ rd /s /q "%APPDATA%\Claude\GPUCache"

Restart the app after clearing the cache. If the app still shows a blank window, uninstall and reinstall it.

Resolve Network and Connectivity Issues

If Claude fails across multiple browsers and devices on the same network, the problem is almost certainly network-level.

Test basic connectivity. Open a terminal and check if you can reach Anthropic’s endpoints:

$ curl -I https://claude.ai
HTTP/2 200
✓ Connection successful

$ curl -I https://api.anthropic.com
HTTP/2 200
✓ API endpoint reachable

If these fail or time out, your network is blocking the connection.

VPN interference. Some VPNs route traffic through regions where Anthropic’s services may be unavailable or experience higher latency. Try disconnecting your VPN temporarily. If Claude works without the VPN, configure split tunneling to exclude claude.ai and api.anthropic.com from the VPN tunnel.

Corporate proxy and firewall. Ask your IT team to whitelist these domains: claude.ai, *.claude.ai, api.anthropic.com, status.anthropic.com, and cdn.anthropic.com. WebSocket connections (used for streaming responses) are commonly blocked by proxies that only allow standard HTTP.

DNS filtering. If you use Pi-hole, NextDNS, or AdGuard DNS, check if claude.ai or anthropic.com appears in your block lists. Some overly aggressive blocklists categorize AI services as trackers.

Mobile data test. Switch your phone to cellular data (turn off Wi-Fi) and try claude.ai in your mobile browser. If it works on cellular but not Wi-Fi, the issue is definitively network-side.

Fix API and Claude Code Failures

Developer environments introduce their own failure modes beyond the web app.

API key validation. The most common API failure is a bad or expired key. Verify yours:

$ curl https://api.anthropic.com/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{"model":"claude-sonnet-4-20250514","max_tokens":10,"messages":[{"role":"user","content":"hi"}]}'
{"id":"msg_...","type":"message",...}
✓ API key valid

If you get 401 Unauthorized, your key is invalid. Generate a new one at console.anthropic.com.

Common API error codes:

• 401 — Invalid API key. Regenerate it.
• 403 — Your account lacks permission for the requested model or feature.
• 429 — Rate limit exceeded. Back off and retry with exponential delay.
• 500 — Server error on Anthropic’s side. Check the status page.
• 529 — Overloaded. Anthropic’s servers are at capacity. Retry after a delay.

Claude Code CLI issues. Claude Code authenticates separately from the web app. If it stops working:

# Check Claude Code version
$ claude --version

# Re-authenticate
$ claude auth login

# If auth flow fails, try clearing stored credentials
$ claude auth logout
$ claude auth login

Environment variable conflicts. If you’ve set ANTHROPIC_API_KEY in your shell profile, Claude Code may use that instead of its OAuth credentials. Check with echo $ANTHROPIC_API_KEY. Unset it if you want Claude Code to use its own auth: unset ANTHROPIC_API_KEY.

A gotcha official docs underplay: Claude Code and the claude.ai web app use entirely separate authentication systems and may have different rate limits. Being logged into claude.ai doesn’t mean Claude Code is authenticated, and vice versa. If one works but the other doesn’t, treat them as independent problems. Similarly, clearing your browser cache has zero effect on CLI issues.

Platform-Specific Checks

Some failures are tied to specific platforms. Find yours below.

Chrome (all platforms): Chrome’s “Memory Saver” feature (introduced in Chrome 108+) can suspend the claude.ai tab if it’s inactive. This kills the WebSocket connection and causes responses to stop mid-stream. Disable it for claude.ai: go to chrome://settings/performance, add claude.ai to the “Always keep these sites active” list.

Safari (macOS/iOS): Safari’s Intelligent Tracking Prevention (ITP) can interfere with claude.ai’s session cookies. If you’re logged out repeatedly, go to Safari → Settings → Privacy and ensure “Prevent cross-site tracking” isn’t blocking claude.ai. On iOS, also check Settings → Safari → Advanced → Experimental Features — some experimental flags can break WebSocket connections.

Firefox: Enhanced Tracking Protection (Strict mode) may block required third-party resources. Switch to Standard mode or add an exception for claude.ai.

iPhone/iPad: Force-close the Safari or Claude app (swipe up from app switcher). Check that your iOS version is current — older versions may lack required WebKit features. If using the Claude iOS app, check the App Store for updates.

Android: Clear the app cache (Settings → Apps → Claude → Storage → Clear Cache). If using a browser, ensure Chrome or your default browser is up to date.

Windows: If you’re behind a corporate environment, check Windows Defender Firewall — it may block outbound WebSocket connections. Also check if your system clock is accurate; TLS certificate validation fails with clock skew beyond a few minutes.

If It Still Fails

If you’ve worked through every step above and Claude still isn’t responding:

1. Capture the exact error. Open browser DevTools (Console and Network tabs) and reproduce the failure. Screenshot any error messages, HTTP status codes, or failed network requests. For CLI issues, run with verbose output if available.

2. Try again later. Some failures are transient server-side issues that don’t appear on the status page immediately. Wait 15-30 minutes and retry.

3. Contact Anthropic support. Report the issue through Anthropic’s support portal. Include: your browser/app version, OS, the exact error message, and the steps you’ve already tried.

4. Check community channels. The Claude Code GitHub issues page is useful for CLI-specific bugs. Other users may have reported the same problem with a workaround.

5. Use an alternative surface temporarily. If claude.ai is down but the API works, you can use the API directly. If both are down, check if third-party integrations (like Cursor or other tools that use the Anthropic API) are also affected — this confirms whether the issue is Anthropic-wide.

FAQ