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

| Code | Error | Cause | Solution | |------|-------|-------|----------| | 400 | Bad Request | Invalid parameters, malformed JSON | Validate all required fields; check model_name is valid | | 401 | Unauthorized | Invalid/expired JWT token | Regenerate JWT; verify AK/SK; check exp claim | | 402 | Payment Required | Insufficient credits | Top up API resource pack or subscription | | 403 | Forbidden | Content policy violation or API disabled | Review prompt against content policy; enable API access | | 404 | Not Found | Invalid task_id or wrong endpoint | Verify task_id; check endpoint path spelling | | 429 | Too Many Requests | Rate limit exceeded | Implement exponential backoff (see pattern below) | | 500 | Internal Server Error | Kling platform issue | Retry after 30s; if persistent, check status page | | 502 | Bad Gateway | Upstream service unavailable | Retry with backoff; typically transient | | 503 | Service Unavailable | System maintenance | Wait and retry; check announcements |

Task-Level Failures

When HTTP returns 200 but task_status is "failed":

| task_status_msg | Cause | Solution | |-------------------|-------|----------| | Content policy violation | Prompt contains restricted content | Remove violent, adult, or copyrighted references | | Image quality too low | Source image is blurry or too small | Use image >= 300x300px, clear and sharp | | Prompt too complex | Too many scene elements | Simplify to 1-2 subjects, clear action | | Generation timeout | Internal processing exceeded limit | Retry; reduce duration from 10s to 5s | | Invalid image format | Unsupported file type | Use JPG, PNG, or WebP | | Mask dimension mismatch | Mask size differs from source | Ensure mask matches source image dimensions exactly |

JWT Authentication Errors

Problem: 401 on every request

python
# 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

python
# 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

python
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

python
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