How to Fix Claude 503 Service Unavailable Error

An HTTP 503 Service Unavailable error on Claude.ai indicates that the platform's servers are temporarily unable to handle your request. Unlike client-side errors, a 503 is almost always caused by server-side issues, such as scheduled maintenance, unexpected system outages, or sudden traffic spikes that overload the hosting infrastructure.

While the root cause usually lies with Anthropic's hosting systems, your browser can sometimes cache this error page, keeping you locked out even after the servers have recovered. Follow these steps to diagnose, bypass cached errors, and get back to using Claude.

1. Check the official status dashboard Before attempting any local troubleshooting, confirm whether the issue is on Anthropic's end.

• Navigate to the official status page at status.anthropic.com.
• Look at the status of the "Claude.ai" component.
• Check the "Past Incidents" log at the bottom of the page to see if engineers are actively resolving an outage.

If the status page shows an active major outage or degraded performance, local troubleshooting will not fix the issue. You must wait for the engineering team to resolve the server-side problem.

2. Perform a hard browser refresh If the status page shows "All Systems Operational," your browser might be displaying a cached version of the 503 error page. A standard refresh just reloads the page from local storage. A hard refresh forces the browser to request the latest version directly from Claude's servers.

• Windows/Linux: Press Ctrl + F5, or hold Ctrl and click the Reload button.
• Mac (Safari): Press Cmd + Option + E to empty the cache, then Cmd + R to reload.
• Mac (Chrome/Firefox): Press Cmd + Shift + R, or hold Shift and click the Reload button.

3. Clear cache and site-specific cookies If a hard refresh does not work, corrupted cookies or outdated session state files may still point to the offline server node. Cleaning Claude's specific site data resolves this without logging you out of other websites.

1. In Google Chrome, click the tune/lock icon to the left of claude.ai in the address bar.
2. Click Site settings or Cookies and site data.
3. Select Manage on-device site data and delete all stored entries for Claude.
4. Close the browser tab, open a new incognito window, and try logging in again.

4. Temporarily disable VPNs and proxies During high-traffic periods, Anthropic uses Content Delivery Networks (CDNs) like Cloudflare to mitigate traffic. These CDNs frequently block or throttle IP addresses associated with commercial VPN services or proxy networks to prevent bot attacks.

If you are using a VPN, disconnect it temporarily and reload Claude. If you are on a restricted corporate or school network, try switching to a mobile hotspot to see if the 503 error clears.

5. Switch to a different browser engine Browser extensions (especially ad blockers, script blockers, or cookie managers) can disrupt the background WebSocket connections that Claude uses to stream responses, triggering false 503 errors.

Try opening Claude in an entirely different browser engine. For example, if you are using a Chromium-based browser (Chrome, Edge, Brave), try switching to a Gecko-based browser (Firefox) or WebKit-based browser (Safari) with all extensions disabled.

When to escalate If the official status page is completely green (operational) but you have experienced a persistent 503 Service Unavailable error for more than 30 minutes across multiple devices and networks, the issue may be localized to your account container.

Contact support by clicking the "Support" or "Help" widget in the lower right corner of the Claude login page, or email support@anthropic.com. Be sure to include your IP address, browser version, and confirmation that you have already cleared your cache.