Claude, the AI assistant developed by Anthropic, has attracted a large user base thanks to its long context window and high-quality responses. In practice, however, many users run into sign-up hiccups, message caps, or error codes. This article rounds up the most frequently asked scenarios to help you resolve common pain points quickly.
What to Do When Registration or Account Linking Fails
Registering for Claude requires a valid email and phone number. If you don't receive the verification code, first check your spam folder or try a different email provider like Gmail or Outlook. As for the phone number, Claude does not support virtual numbers (e.g., Google Voice); using a real SIM card is recommended (numbers with +86 country code are supported, though overseas SMS may occasionally be blocked). If you see "This phone number is already in use," it means you've previously registered for another Anthropic service—just try a different number. When linking a third-party account (e.g., Google), make sure your browser is not in private/incognito mode, or the redirect may fail.
Message Limit Exceeded or Request Errors
The free tier of Claude has an hourly message cap (roughly 30 messages) and a daily total limit. When you hit the limit, the interface will display "You’ve run out of messages." Simply wait for the reset (typically every 3 hours). If you frequently encounter "Request failed with status code 429," it means you are sending requests too fast—try to wait at least 5 seconds between each query. For Pro users who get a "429" error, first check whether your API key has expired or run out of quota, then verify your subscription status in the account dashboard.
Claude's Response Is Incomplete or Cut Off
When the conversation context exceeds Claude's maximum token limit (roughly 128k for the free version and 200k for Pro), the model will automatically truncate its response. If you upload a long PDF, Claude may only analyze the first part. The workaround is to split the text: break large files into smaller sections and ask questions in batches. Additionally, if your network connection is unstable, the response may drop mid-stream; refreshing the page or switching to a 5G/Wi-Fi connection can help.
File Upload Failures and Format Restrictions
Claude supports PDF, TXT, CSV, and images (JPG/PNG), but individual files cannot exceed 10 MB. Common reasons for upload failure include: file names containing special characters (e.g., Chinese brackets or spaces), and file encoding not being UTF-8 (especially for CSV). If an image is uploaded but not recognized, try cropping it to a square shape using a screenshot tool and then re-upload. If the upload spinner keeps spinning without a response, a browser plugin conflict might be the cause—try disabling ad blockers and retry.
Account Locked or Suspicious Login Handling
Claude may trigger a security lock when it detects multiple devices logged in simultaneously or a login from an unusual IP address. In such cases, your account will be temporarily locked. You will receive a verification email at your registered address; click the link to unlock it. To avoid frequent locks, avoid using public VPNs (especially those that switch nodes often). If the account still shows "Account suspended" after unlocking, contact Anthropic's official support by emailing support@anthropic.com, explaining your usage scenario (e.g., study or work). The issue is usually resolved within 24 hours.
