APIConnectionError
openai.APIConnectionError (when routing to Qwen DashScope via OpenAI SDK)
Stack trace
openai.APIConnectionError: Connection error: Unable to establish a connection to https://api.openai.com/v1/chat/completions (Failed to resolve 'api.openai.com' for url https://api.openai.com/v1/chat/completions) Or: HTTPError: 404 Not Found — The requested URL was not found on this server. Expected: https://dashscope.aliyuncs.com/api/v1/services/aigc/text-generation/generation or similar Qwen endpoint
Why it happens
Qwen's DashScope service provides an OpenAI-compatible API endpoint, but the base_url must point to Qwen's servers (dashscope.aliyuncs.com or regional variant), not OpenAI's. When you initialize the OpenAI SDK without specifying base_url, it defaults to api.openai.com. Additionally, the DashScope endpoint structure differs from OpenAI's: Qwen uses `/api/v1/services/aigc/text-generation/generation` while OpenAI uses `/v1/chat/completions`. The SDK's path-rewriting logic may not correctly map between these incompatible structures.
Detection
Test your endpoint connectivity before deploying by making a simple HEAD or GET request to your base_url. Enable debug logging in the OpenAI SDK with `import logging; logging.basicConfig(level=logging.DEBUG)` to see the actual URL being requested and compare it against Qwen DashScope's documented endpoint.
Causes & fixes
base_url parameter is missing or defaults to OpenAI's endpoint
Explicitly set base_url to Qwen DashScope: `client = OpenAI(api_key=os.environ['DASHSCOPE_API_KEY'], base_url='https://dashscope.aliyuncs.com/compatible-mode/v1')`
Using incorrect DashScope region or deprecated endpoint URL
Use the correct region-specific endpoint. For mainland China use `https://dashscope.aliyuncs.com/compatible-mode/v1`, for international use `https://dashscope-intl.aliyuncs.com/compatible-mode/v1`, and verify the endpoint hasn't changed in Qwen's docs.
API key is for wrong service (OpenAI key instead of DashScope key) or missing altogether
Ensure api_key is set to your DashScope API token from https://dashscope.console.aliyun.com, not an OpenAI key. Set it via: `api_key=os.environ['DASHSCOPE_API_KEY']` and verify the env var is exported.
OpenAI SDK version is too old and doesn't support the base_url parameter correctly with Qwen's path structure
Upgrade to OpenAI SDK v1.3.0+ which includes improved base_url handling: `pip install --upgrade openai>=1.3.0`
Code: broken vs fixed
import os
from openai import OpenAI
# BROKEN: Missing base_url defaults to OpenAI's endpoint, causing routing failure
client = OpenAI(
api_key=os.environ.get('DASHSCOPE_API_KEY')
# base_url is not set — defaults to https://api.openai.com/v1
)
response = client.chat.completions.create(
model='qwen2.5-7b-instruct', # Qwen model on DashScope
messages=[{'role': 'user', 'content': 'Hello'}]
)
print(response.choices[0].message.content)import os
from openai import OpenAI
# FIXED: Explicitly set base_url to Qwen DashScope's OpenAI-compatible endpoint
client = OpenAI(
api_key=os.environ['DASHSCOPE_API_KEY'], # Set env var: export DASHSCOPE_API_KEY='sk-...'
base_url='https://dashscope.aliyuncs.com/compatible-mode/v1' # Correct Qwen endpoint
)
response = client.chat.completions.create(
model='qwen2.5-7b-instruct', # Qwen model on DashScope
messages=[{'role': 'user', 'content': 'Hello'}]
)
print(response.choices[0].message.content)Workaround
If you cannot immediately update your environment variables, hardcode the base_url as a fallback in your client initialization: `base_url=os.environ.get('QWEN_BASE_URL', 'https://dashscope.aliyuncs.com/compatible-mode/v1')`. This allows override via env var but doesn't fail silently. For multiple regions, create a helper function: `def get_dashscope_endpoint(region='cn'): endpoints = {'cn': 'https://dashscope.aliyuncs.com/compatible-mode/v1', 'intl': 'https://dashscope-intl.aliyuncs.com/compatible-mode/v1'}; return endpoints.get(region, endpoints['cn'])`
Prevention
Create a centralized configuration module (e.g., `config.py`) that validates all LLM endpoints at startup. Load endpoint URLs from environment variables with validation: `DASHSCOPE_BASE_URL = os.environ.get('DASHSCOPE_BASE_URL', '').strip(); assert DASHSCOPE_BASE_URL.startswith('https://'), 'Invalid base_url'`. Test endpoint connectivity in your CI/CD pipeline with a simple health check before deploying. Use type-hinted factory functions that return configured clients to prevent re-initialization mistakes: `def create_qwen_client() -> OpenAI: return OpenAI(api_key=..., base_url=...)`