Claude Error Troubleshooting: Fix Login Failures & API Request Issues

Encountering errors while using Claude can be frustrating, whether it's the web version getting stuck at the verification step or the API returning unusual error codes—both can interrupt your workflow. This article covers the most common Claude error types and manual fixes, without referencing any tools or model versions. It only provides actionable steps based on actual system feedback.

Login Failures & Account Lockout Issues

When logging in, the most common causes of "Invalid credentials" or "Account temporarily locked" prompts are multiple incorrect password attempts or logins from unusual locations triggering security measures. First, check your email for any unusual login alerts from Claude. If your account is locked, you typically need to wait 15 to 30 minutes for it to unlock automatically—do not keep retrying.

If you're stuck on the "Verification code" step, check both your inbox and spam folder for a 6-digit code. Some email providers may delay delivery by 5 to 10 minutes. Try requesting a new verification code from your registered email, and ensure your browser isn't blocking pop-ups. If you still don't receive it, switch to a different network (e.g., use your phone's hotspot) and try again.

API Error Code Breakdown

Common Claude API error codes include 400 Bad Request (incorrect request parameters or format), 401 Unauthorized (invalid or expired API key), and 429 Too Many Requests (rate limit reached). A 400 error usually means unsupported parameters or a malformed JSON structure—double-check for missing commas or quotes, especially on the last line.

For a 401 error, first verify that your API key is copied exactly, with no extra spaces. If you just generated a new key and get a 401 immediately, wait about 2 minutes before retrying, as there can be a short delay before the key becomes active. A 429 error means you've exceeded the rate limit; typically waiting 60 seconds before retrying resolves it. You can also reduce concurrency or implement exponential backoff logic.

Network Connection & Model Timeout Issues

If you see "Network Error" or "Request timed out," first check if your local proxy or VPN is stable. Claude's API is sensitive to network latency in certain regions—try switching nodes or disabling the proxy for testing. On the web, if you encounter "Service Unavailable," it's usually temporary server overload. Refresh the page or try a different browser.

If you haven't received a response for more than 30 seconds, your input may be too long and hitting the context limit. Try shortening your message or sending it in segments. Also, avoid opening multiple Claude tabs in the same browser at the same time, as this can cause WebSocket conflicts. Keep only one active session open.