Description

Improves error messages & logging:

http streaming enabled + app setting disabled or not set

Worker failed to index functions
Result: Failure
Exception: AppSettingDisabledError: HTTP Streaming is enabled but 
PYTHON_ENABLE_INIT_INDEXING is not set or is set to false. 
See aka.ms/functions-python-streaming for more information

function-parameter mismatch

@app.timer_trigger(
    schedule="0 */30 * * * *", arg_name="myTimer"
)
async def healthcheck() -> None:
    pass

Worker failed to index functions
[2025-08-20T19:12:07.676Z] Result: Failure
Exception: FunctionLoadError: cannot load the healthcheck function: 
the following parameters are declared in the function definition (function.json 
or function decorators) but not in Python: {'myTimer'}

function-parameter mismatch version 2

@app.timer_trigger(
    schedule="0 */30 * * * *", arg_name="myTimer"
)
async def healthcheck(myTimer, test) -> None:
    pass

Worker failed to index functions
Result: Failure
Exception: FunctionLoadError: cannot load the healthcheck function: 
the following parameters are declared in Python but not in the function 
definition (function.json or function decorators):  {'test'}

Fixes # #1716

Pull Request Checklist

Host-Worker Contract

• Does this PR impact the host-worker contract (e.g., gRPC messages, shared interfaces)?
  • If yes, have the changes been applied to:
    • azure_functions_worker (Python <= 3.12)
    • proxy_worker (Python >= 3.13)
  • If no, please explain why:

Worker Execution Logic

• Does this PR affect worker execution logic (e.g., function invocation, bindings, lifecycle)?
  If yes, please answer the following:

Python Version Coverage

• Does this change apply to both Python <=3.12 and 3.13+?
• If yes, have the changes been made to:
  • azure_functions_worker (Python <= 3.12)
  • runtimes/v1 / runtimes/v2 (Python >= 3.13)
• If no, please explain why:

Programming Model Compatibility (for Python 3.13+)

• Does this change apply to both:
  • V1 programming model (runtimes/v1)?
  • V2 programming model (runtimes/v2)?
• Explanation (if limited to one model):