AzureOpenAi is unable to process chat.completions when the API version is set to preview.

[hsuyuming]

Confirm this is an issue with the Python library and not an underlying OpenAI API

• This is an issue with the Python library

Describe the bug

When we attempt to use "chat.completions.create" and set the api-version to "preview," we receive the following error: "openai.NotFoundError: Error code: 404 - {'error': {'code': '404', 'message': 'Resource not found'}}."

Root cause

The root cause of this error is that Azure has changed how the "preview" API version works. They now use base_url instead of azure_endpoint, and the new endpoint for /chat/completions is https://your-resource-name.openai.azure.com/openai/v1/chat/completions?api-version=preview. However, the current SDK code tries to add /deployments/{model} to the URL, resulting in `https://your-resource-name.openai.azure.com/openai/v1/openai/deployments/gpt-5-chat/chat/completions?api-version=preview``, which is incorrect. This causes the resource not found error.

Suggestion:

Now

@override
    def _build_request(
        self,
        options: FinalRequestOptions,
        *,
        retries_taken: int = 0,
    ) -> httpx.Request:
        if options.url in _deployments_endpoints and is_mapping(options.json_data):
            model = options.json_data.get("model")
            if model is not None and "/deployments" not in str(self.base_url.path):
                options.url = f"/deployments/{model}{options.url}"

        return super()._build_request(options, retries_taken=retries_taken)

After

@override
    def _build_request(
        self,
        options: FinalRequestOptions,
        *,
        retries_taken: int = 0,
    ) -> httpx.Request:
        if options.url in _deployments_endpoints and is_mapping(options.json_data):
            model = options.json_data.get("model")
            if model is not None and self._api_version not in ["preview", "latest"] and "/deployments" not in str(self.base_url.path):
                options.url = f"/deployments/{model}{options.url}"

        return super()._build_request(options, retries_taken=retries_taken)

Reference:
[1] https://learn.microsoft.com/en-us/azure/ai-foundry/openai/api-version-lifecycle?tabs=entra#next-generation-api-1
[2] https://learn.microsoft.com/en-us/azure/ai-foundry/openai/reference-preview-latest#create-chatcompletion
[3] https://github.com/openai/openai-python/blob/main/src/openai/lib/azure.py#L65-L66

https://learn.microsoft.com/en-us/azure/ai-foundry/openai/reference-preview-latest#create-chatcompletion

To Reproduce

1. Create virtual env

python -m venv .venv
source .venv/bin/activate
pip install openai==1.101.0
pip install azure-identity

2. create testing code

from openai import AzureOpenAI
from azure.identity import DefaultAzureCredential, get_bearer_token_provider

token_provider = get_bearer_token_provider(
    DefaultAzureCredential(), "https://cognitiveservices.azure.com/.default"
)

client = AzureOpenAI(  
  base_url = "https://YOUR-RESOURCE-NAME.openai.azure.com/openai/v1/",  
  azure_ad_token_provider=token_provider,
  api_version="preview"
)

response = client.chat.completions.create(
    model="gpt-5-chat",
    messages=[
        {"role": "user", "content": input},
    ]
)

print(response.model_dump_json(indent=2)) 

3. python test.py

(.venv) user@xxx:~/genai_workshop/azure_workshop$ python test.py 
> /home/user/genai_workshop/azure_workshop/call_o1_model.py(33)<module>()
-> openai_client = AzureOpenAI(
(Pdb) c
Current model you are using gpt-5-chat
> /home/user/genai_workshop/.venv/lib/python3.10/site-packages/openai/lib/azure.py(66)_build_request()
-> if model is not None and "/deployments" not in str(self.base_url.path):
(Pdb) c
> /home/user/genai_workshop/.venv/lib/python3.10/site-packages/openai/_base_client.py(983)request()
-> response = self._client.send(
(Pdb) c
Traceback (most recent call last):
  File "/home/user/genai_workshop/azure_workshop/call_o1_model.py", line 41, in <module>
    response = openai_client.chat.completions.create(
  File "/home/user/genai_workshop/.venv/lib/python3.10/site-packages/openai/_utils/_utils.py", line 287, in wrapper
    return func(*args, **kwargs)
  File "/home/user/genai_workshop/.venv/lib/python3.10/site-packages/openai/resources/chat/completions/completions.py", line 1147, in create
    return self._post(
  File "/home/user/genai_workshop/.venv/lib/python3.10/site-packages/openai/_base_client.py", line 1260, in post
    return cast(ResponseT, self.request(cast_to, opts, stream=stream, stream_cls=stream_cls))
  File "/home/user/genai_workshop/.venv/lib/python3.10/site-packages/openai/_base_client.py", line 1048, in request
    raise self._make_status_error_from_response(err.response) from None
openai.NotFoundError: Error code: 404 - {'error': {'code': '404', 'message': 'Resource not found'}}

Code snippets

from openai import AzureOpenAI
from azure.identity import DefaultAzureCredential, get_bearer_token_provider

token_provider = get_bearer_token_provider(
    DefaultAzureCredential(), "https://cognitiveservices.azure.com/.default"
)

client = AzureOpenAI(  
  base_url = "https://YOUR-RESOURCE-NAME.openai.azure.com/openai/v1/",  
  azure_ad_token_provider=token_provider,
  api_version="preview"
)

response = client.chat.completions.create(
    model="gpt-5-chat",
    messages=[
        {"role": "user", "content": input},
    ]
)

print(response.model_dump_json(indent=2))

OS

linux

Python version

Python 3.10.12

Library version

1.101.0