Claude Login & API Error Troubleshooting: Complete Guide from Login Failure to Request Timeout

When using Claude, you may run into various error messages on the web login page or during API calls. This article breaks down the most frequent error types with real-world scenarios and manual fixes, so you can restore your conversation or API service fast.

Login Failure: “Invalid credentials” or “Account locked”

If you enter the correct email and password but still see “Invalid credentials,” it’s usually because multiple incorrect password attempts have triggered a temporary lockout. Wait 15–30 minutes and try again, or use the “Forgot password” option to reset your password.

If the error says “Account locked” and you just signed up, your email verification might not be complete. Check your inbox (and spam folder) for the Claude verification email, then click the link to activate your account. Some corporate email servers block verification messages, so using Gmail or Outlook is recommended.

API Request Returns “401 Unauthorized”

This error almost always means your API key is invalid or not sent correctly. First, double‑check that your request header includes Authorization: Bearer YOUR_API_KEY. If the key was generated just now, it may take a few minutes to sync.

Also, Claude API keys come in project‑level and user‑level variants—mixing them results in a 401 error. Verify the permissions associated with your key and make sure you’re using the correct endpoint. For example, the chat/completions endpoint requires specific access rights.

Frequent “429 Too Many Requests”

This is the most common rate‑limiting error. Free accounts typically allow only 30 requests per minute—exceeding that triggers a 429. Check the official documentation for the rate limit table, then adjust your request interval according to your plan.

If you’re on a paid Pro or Team plan, you can implement automatic retries by using the “Retry‑After” header value. A good practice is to use exponential backoff in your code: start with a 1‑second wait and double it after each failure.

Session Interruption: “Session expired” or “Connection reset”

On the web, being inactive for a long time will automatically log you out as a security measure. Simply log back in. If “Connection reset” appears frequently, it may be caused by network instability or proxy settings. Try turning off your VPN or switching to a different node.

Another common cause is browser cache conflicts. Clear your cookies and cache (especially anything related to claude.ai), then restart your browser. If the issue persists, try incognito mode or switch to Edge or Firefox.

For any of the issues above, follow the troubleshooting steps—most can be resolved on your own. If the error persists, take a screenshot with the timestamp and request ID and submit it to Claude’s official support. They usually reply within one business day.