Claude code error code explanation

I. 4xx Client Errors (Requires Code/Configuration Modification)

400 invalid_request_error

Meaning: Incorrect request format/parameters
Common: Invalid JSON, incorrect parameter names, incorrect model names, excessively long prompts
Solution: Check the request body, parameter names, and model names; do not retry directly.

401 authentication_error

Meaning: Authentication failed; invalid/missing API key
Common: No key, incorrect key, expired key, revoked key, prefix not sk-ant-api03-
Solution: Verify the key, regenerate it, check environment variables.

402 billing_error

Meaning: Billing/payment problem
Common: Insufficient balance, expired credit card, account frozen due to outstanding fees
Solution: Top up via console, update payment method.

403 permission_error

Meaning: Insufficient permissions
Common: Key does not have permission to access the model/ Interface, region restrictions, organization disabled

Solution: Check role permissions, switch to an available region (Claude)

404 not_found_error

Meaning: Resource does not exist (Claude)

Common: Incorrect model name, incorrect endpoint path, resource ID does not exist

Solution: Verify model name (e.g., claude-3-5-sonnet-20260620) and interface address

413 request_too_large

Meaning: Request body too large (Claude)

Limit: Standard interface maximum 32MB, prompt + context exceeds length

Solution: Shorten prompt, batch upload, reduce context (Claude)

422 unprocessable_entity

Meaning: Content violation / policy not approved

Common: Sensitive content, prohibited topics, security policy blocking

Solution: Modify prompt, remove sensitive content, do not retry

429 rate_limit_error

Meaning: Rate limit exceeded (Claude)

Type:
RPM: Requests per minute exceeded
TPM: Requests per minute exceeded Exceeding Limits
Concurrent Requests Exceed Limits
Response: Usually includes "Retry-After: X seconds"
Handling: Must back off and retry (exponential backoff), rate limiting, frequency reduction

II. 5xx Server-Side Errors (Retryable)

500 api_error

Meaning: Unknown internal server error (Claude)
Handling: Retry after a brief backoff; contact official support after multiple failures.

529 overloaded_error (Commonly returns 503)

Meaning: Server overload/busy/maintenance
Handling: Retry at longer intervals (10–30 seconds), stagger requests.

503 Gateway Timeout

Meaning: Server gateway timed out; the backend will retry.

Handling: Retry after a brief backoff; contact official support after multiple failures.

Claude code error code explanation

I. 4xx Client Errors (Requires Code/Configuration Modification)#

400 invalid_request_error#

401 authentication_error#

402 billing_error#

403 permission_error#

404 not_found_error#

413 request_too_large#

422 unprocessable_entity#

429 rate_limit_error#

II. 5xx Server-Side Errors (Retryable)#

500 api_error#

529 overloaded_error (Commonly returns 503)#

503 Gateway Timeout#