Kling AI Common Errors

Overview

Complete error reference for the Kling AI API. Covers HTTP status codes, task-level failures, JWT issues, and generation-specific problems with tested solutions.

HTTP Error Codes

400

model_name

401

exp

402

403

404

429

500

502

503

Task-Level Failures

When HTTP returns

200

task_status

"failed"

task_status_msg

JWT Authentication Errors

Problem:

401

on every request

# WRONG — missing headers parameter
token = jwt.encode(payload, sk, algorithm="HS256")

# CORRECT — include explicit headers
token = jwt.encode(payload, sk, algorithm="HS256",
                   headers={"alg": "HS256", "typ": "JWT"})

Problem: Token works then fails after 30 min

# WRONG — token generated once at import time
TOKEN = generate_token()

# CORRECT — refresh before expiry
class TokenManager:
    def __init__(self, ak, sk):
        self.ak, self.sk = ak, sk
        self._token = None
        self._exp = 0

    @property
    def token(self):
        if time.time() >= self._exp - 300:  # 5 min buffer
            payload = {"iss": self.ak, "exp": int(time.time()) + 1800,
                       "nbf": int(time.time()) - 5}
            self._token = jwt.encode(payload, self.sk, algorithm="HS256",
                                     headers={"alg": "HS256", "typ": "JWT"})
            self._exp = int(time.time()) + 1800
        return self._token

Rate Limit Handling

import time
import requests

def request_with_backoff(method, url, headers, json=None, max_retries=5):
    """Retry with exponential backoff on 429 and 5xx errors."""
    for attempt in range(max_retries):
        response = method(url, headers=headers, json=json)

        if response.status_code == 429:
            retry_after = int(response.headers.get("Retry-After", 2 ** attempt))
            print(f"Rate limited. Retrying in {retry_after}s...")
            time.sleep(retry_after)
            continue
        elif response.status_code >= 500:
            wait = 2 ** attempt
            print(f"Server error {response.status_code}. Retrying in {wait}s...")
            time.sleep(wait)
            continue

        response.raise_for_status()
        return response

    raise RuntimeError(f"Max retries ({max_retries}) exceeded")

Diagnostic Checklist

When a generation fails, check in order:

1. Auth valid? — Test with a simple GET request first
2. Credits available? — Check balance in developer console
3. Model valid? — Verify

   model_name

   matches catalog exactly
4. Parameters valid? —

   duration

   must be

   "5"

   or

   "10"

   (string, not int)
5. Prompt clean? — Remove special characters, keep under 2500 chars
6. Image accessible? — For I2V, verify image URL is publicly accessible
7. Feature exclusivity? —

   image_tail

   ,

   dynamic_masks

   , and

   camera_control

   are mutually exclusive

Debug Logging

import logging

logging.basicConfig(level=logging.DEBUG)
logger = logging.getLogger("kling")

def debug_request(method, url, headers, json=None):
    """Log request/response for debugging."""
    logger.debug(f"→ {method.__name__.upper()} {url}")
    logger.debug(f"→ Body: {json}")
    r = method(url, headers=headers, json=json)
    logger.debug(f"← Status: {r.status_code}")
    logger.debug(f"← Body: {r.text[:500]}")
    return r

Resources

• API Reference
• Content Policy
• Developer Portal