DeepSeek API Errors and Troubleshooting

DeepSeek documents seven common API status codes: 400, 401, 402, 422, 429, 500 and 503. Fix client errors before retrying; back off only for transient limits or server failures. Also verify that the model ID is current—legacy deepseek-chat and deepseek-reasoner aliases were retired in July 2026.

Error table

Do not return raw provider errors containing private prompts or internal details to end users.

400: invalid format

Check JSON syntax, message roles and DeepSeek-specific fields. In thinking-mode tool sequences, the official guide requires reasoning_content to be passed back after a tool call. Missing it can cause a 400.

Confirm the request uses Chat Completions rather than an unsupported endpoint shape. Log a redacted body schema, not content. Repeating the same invalid request will not help.

401: authentication failed

Ensure the key came from the official DeepSeek platform and the Authorization header is correct. Remove leading or trailing whitespace. Confirm the application reads the expected environment, not a missing development variable.

If a key appeared in source control, logs or a public client, revoke it even if it still works. Replace it in the secret store and review usage. Never ask a user to paste a provider key into a support form.

402: insufficient balance

Open the official account balance. DeepSeek separates granted and topped-up balance. A key can be valid while the account cannot pay for the request.

Do not loop retries or silently switch to someone else’s key. Raise a billing alert and pause nonessential jobs. The pricing guide explains current rates and granted-balance limitations.

422: invalid parameters

Inspect the error field and current API reference. Common causes include an unsupported model, wrong type, excessive value or incompatible combination. Thinking mode ignores certain sampling parameters, while beta features can require a different base URL.

Validate request objects locally with types and schemas. Pin accepted model IDs. A current model-list check can catch obsolete configuration during deployment.

429: rate or concurrency limit

DeepSeek currently documents account-level concurrency of 2,500 for V4 Flash and 500 for V4 Pro. Each open request counts until completion. Limits are shared across keys in the account.

Use exponential backoff with random jitter, a retry cap and a queue. Reduce unnecessary parallelism and cancel abandoned streams. Adding more keys under the same account does not bypass an account-level limit.

500 and 503

These are server-side or overload conditions. Retry after a short delay, then fail cleanly. Preserve the time, model, endpoint and provider request identifier for official support. Check status.deepseek.com↗ — official external destination for incidents.

Do not retry forever. A retry storm makes overload worse and can duplicate downstream tool actions. Use a circuit breaker for sustained failure.

Timeouts and keep-alives

DeepSeek’s rate-limit documentation says long requests may send blank lines for non-streaming responses or SSE keep-alive comments for streams. A client must tolerate these while still enforcing an overall deadline.

Set connect, read and total timeouts appropriate to the task. On client cancellation, close the upstream connection. If long thinking tasks exceed product expectations, reduce effort, context or output rather than only increasing timeouts.

Retired model errors

The V4 release scheduled deepseek-chat and deepseek-reasoner for full retirement after 2026-07-24. Use deepseek-v4-flash or deepseek-v4-pro and rerun behaviour tests.

Do not create a silent alias inside your application without recording the change. Model migration can affect tokenisation, reasoning, tool behaviour and cost.

JSON and tool failures

JSON mode can return empty content or truncated output. Check finish reason, parse and validate. Tool arguments can contain invalid JSON or unexpected parameters; reject them before execution.

These are application-level failures even when HTTP status is 200. Monitor parse, schema and business-rule error rates separately from transport status.

Regional, DNS and TLS problems

If the status page is normal but all requests fail to connect, test DNS resolution, certificate validation, proxy and firewall rules. Do not disable TLS verification. Confirm the system clock and corporate proxy trust chain.

Availability can vary by jurisdiction under DeepSeek’s terms. Use official support for account or regional questions rather than an unverified proxy.

A production incident checklist

Capture start time and timezone, affected models, error distribution, request volume, deployment changes and status-page state. Pause aggressive retries, protect queues and communicate impact without claiming a provider outage until verified.

After recovery, calculate dropped, delayed and duplicated tasks. Rotate credentials if exposure was possible. Add a regression test or alert for the root cause.

The DeepSeek API setup guide provides a known-good request shape. If both chat and API appear affected, use the broader DeepSeek connection guide to separate service incidents from local failures.

Conclusion

DeepSeek troubleshooting is fastest when client, account, capacity and provider failures are separated. Fix 400-class requests, back off transient errors, verify current model IDs and consult the official status page before declaring an outage.