Error Handling

Comprehensive guide to handling errors when using the Claude API

title: Error Handling description: Comprehensive guide to handling errors when using the Claude API

Proper error handling ensures your applications remain robust and provide good user experiences even when things go wrong. This guide covers all error types, handling patterns, and best practices.

Error Categories

HTTP Status Codes

| Status | Name | Description | |--------|------|-------------| | 400 | Bad Request | Invalid request format or parameters | | 401 | Unauthorized | Invalid or missing API key | | 403 | Forbidden | API key lacks required permissions | | 404 | Not Found | Invalid endpoint or model | | 429 | Rate Limited | Too many requests | | 500 | Server Error | Internal API error | | 529 | Overloaded | API is temporarily overloaded |

Error Response Format

Error Types

invalid_request_error

Request is malformed or has invalid parameters.

Common causes:

• Missing required fields
• Invalid parameter values
• Malformed JSON

Example handling:

authentication_error

API key is invalid, expired, or missing.

permission_error

API key doesn't have permission for the requested action.

not_found_error

Requested resource (model, endpoint) doesn't exist.

rate_limit_error

Too many requests or tokens in a time period.

overloaded_error

API is temporarily overloaded.

Comprehensive Error Handling

TypeScript Pattern

Python Pattern

Retry Strategies

Exponential Backoff

Rate Limit Handling

Streaming Error Handling

Handling Mid-Stream Errors

Reconnection Logic

User-Facing Error Messages

Mapping Errors to User Messages

Logging and Monitoring

Structured Error Logging

Error Metrics

Track error rates for monitoring:

Best Practices

1. Always catch errors - Never let API errors crash your application

2. Be specific - Handle different error types appropriately

3. Retry intelligently - Use exponential backoff with jitter

4. Don't retry client errors - 400-level errors (except 429) won't succeed on retry

5. Log comprehensively - Include request IDs for debugging

6. Provide user feedback - Show appropriate messages for different errors

7. Set timeouts - Prevent indefinite waits

8. Monitor error rates - Track and alert on unusual patterns

Next Steps

• Rate limits and quotas
• Streaming responses
• Model comparison