Fix Claude 'Connection Lost. Retrying...' Error Banner

Understanding the "Connection Lost. Retrying..." Loop

Claude.ai uses long-lived Server-Sent Events (SSE) and persistent TCP-based WebSocket connections to stream responses dynamically to your browser. This technology keeps a continuous network tunnel open so tokens can load instantly on your screen without requiring a constant page-by-page refresh cycle.

When the grey or orange banner stating "Connection lost. Retrying..." appears at the top of the interface, it means your browser has dropped this underlying persistent tunnel. If your browser fails to reconnect after several automated attempts, it gets stuck in a loop. This is typically caused by competing browser sessions, local firewalls that reject long-lived connection streams, or corrupted browser service workers.

How to Resolve the Connection Lost Loop

1. Close Dormant Claude Tabs and Sessions

Anthropic limits the number of concurrent WebSocket connections a single user account can have open simultaneously to prevent denial-of-service behaviors. If you have several open tabs containing historical Claude conversations, they may compete for the active stream.

1. Scan all open browser windows and devices (including smartphones and tablets).
2. Close every tab running Claude.ai, leaving only one active tab open.
3. If you use third-party browser extensions that embed Claude into sidebars, temporarily close or disable those tools.
4. Perform a hard refresh (Ctrl + F5 on Windows, or Cmd + Shift + R on macOS) on the single remaining Claude tab.

2. Disable WebSocket Interceptors and Ad-Blockers

Certain security extensions, script blockers, and aggressive ad-blockers inspect dynamic scripts and can mistakenly flag Claude's WebSocket connection requests (wss://) as tracking scripts or unapproved communication protocols.

1. Click the extensions puzzle-piece icon in your browser's toolbar.
2. Locate ad-blockers (such as uBlock Origin or Adblock Plus) or privacy tools (like Privacy Badger).
3. Toggle the extension off specifically for claude.ai.
4. If you use a script-blocking tool (like NoScript), ensure that the domains *.anthropic.com and *.claude.ai are explicitly whitelisted to run all inline and external scripts.

3. Force-Reset Browser Service Workers

Service workers run in the background of your browser to cache assets and manage offline sync functions. If a service worker crashes during a temporary server blip, it will persistently serve cached offline indicators and loop the "Connection lost" banner, even if your physical internet connection has recovered.

1. With Claude.ai open in Chrome, Edge, or Brave, press F12 to open Developer Tools.
2. Navigate to the Application tab at the top of the panel.
3. In the left-hand menu, click on Service Workers under the Application section.
4. Locate the service worker registered for https://claude.ai.
5. Click Unregister on the right.
6. Reload the webpage. This forces your browser to pull down a fresh, uncorrupted version of the service worker from Anthropic's servers.

4. Configure Local Firewalls for Persistent TCP Connections

Some router firewalls, workplace network security systems, or parental control software treat persistent WebSocket traffic as an anomalous connection pool and terminate it after 30 to 60 seconds of activity.

1. Try logging in using your browser's Incognito or Private Browsing mode. If the connection holds, the issue is tied to a local browser profile or cookie configuration.
2. If the connection fails in Incognito mode, temporarily switch your network connection from your current router to a mobile hotspot.
3. If the hotspot works, you must adjust your local router settings to permit long-lived TCP connections, or update your security software's web filtering parameters to bypass deep inspection for *.claude.ai.

When to Escalate

If the connection lost banner persists on multiple devices, across different network environments, and in all browsers, the problem likely lies in a regional routing conflict within Cloudflare's network or a direct database outage on Anthropic's side. Check the operational status at status.anthropic.com first. If all indicators are green, click the "Support" option at the bottom of the Claude side menu to report the persistent connectivity loop, noting that you have cleared your browser service workers and verified your local ports.