local debug azure function fail with error - Value cannot be null. (Parameter 'provider')

Question

I try to local debug the azure function, but got issue. Actually I just follow the instruction to build and tested with below link, but not work.

The instruction is here Debug the Azure Functions Python code locally, and I did not modified the code at all.

While I try to run debug, it pop up error.

Executing task: .venv\Scripts\activate ; func host start

Found Python version 3.8.6 (py).

Azure Functions Core Tools Core Tools Version: 3.0.3160 Commit hash: 00aa7f43cc5c5f15241b5e6e5363256f19ceb990 Function Runtime Version: 3.0.14916.0

Value cannot be null. (Parameter 'provider')

Terminal will be reused by tasks, press any key to close it.

I have no idea what's wrong after I search lots of topic in GitHub or stackoverflow. Finally I remove the azure function extensionBundle in the host.json as a workaround.

Did anyone encounter the same issue with me?

Below is my environment: Windows 10 Python 3.8.6 Function Core Tools Version:3.0.3160 python packages azure-functions 1.50

Answer 1

Try changing your Azure Function Core Tools version.

I was on 4.0.3971, the function started fine.

Upgraded to 4.0.4670 (latest at the time), got the same error as you did.

Reverted to 4.0.3971, worked fine.

Answer 2

Another thing why local debugging might not work is low internet connection. I had such a case with same "Value cannot be null. (Parameter 'provider')" error when trying to work from a hotel with bad (low speed and not stable) internet connection.

Answer 3

Maybe you can try to open the Command Palette (F1), select the Python: Select Interpreter command, and then select the virtual environment in the local .venv folder

Or you can change host.json, extensionBundle requires a higher version.