azure-functions-core-tools: Can't determine project language from files

For me was because of nested configuration setting, forgot it wasn’t supported…

I had a similar issue even though I do have local.settings.json. Adding FUNCTIONS_WORKER_RUNTIME to it solved the issue for me. https://docs.microsoft.com/en-us/azure/azure-functions/functions-app-settings#functions_worker_runtime

If local.settings.json contains information that’s always required, why is it added to .gitignore?

@garrytrinder, do you happen to be missing local.settings.json in your function app directory? If so, I would recommend you run func init in the function app directory and select dotnet and retry.

Mine was caused by having a semi-colon at the end of a key-value-pair instead of a comma in my local.settings.json file. Not a great error message 😃

My solution was that as I was upgrading between VS 2022 Preview, to VS 2022 RC some of my file properties were changed from “Copy if newer” to “do not copy”… when I changed that setting for local.settings.json it resolved the issue.

I. I am encountering this issue too from Visual Studio Update (from 17.5.3 or 17.5.2 maybe).

My Azure functions project that target .NET6 successfully run localy from my Visual Studio few weeks ago.

And not now, without any changes to my local.settings.json, it’s not wokrs.

I have the required keys in settings.json (FUNCTIONS_WORKER_RUNTIME) and valid build action.

A breaking change / regression in the recents versions of Visual Studio ?

Can we have some news please ?

If local.settings.json contains information that’s always required, why is it added to .gitignore?

+1. Without FUNCTIONS_WORKER_RUNTIME defined in local.settings.json, func start or func azure functionapp publish will complain about unknown language.

Annoyingly, --csharp and the other parameters are entirely unsupported on func azure functionapp publish, so you just get a broken function app - but that’s a separate issue [edit: I can’t seem to repro this anymore after calling func init again, but initially it was failing with ‘unknown argument’ when I tried to add --csharp to the az azure functionapp publish]

If one does check in local.settings.json into Git (so that the others and the pipeline have the default values for FUNCTIONS_WORKER_RUNTIME and can deploy successfully), you can’t tell Git to ignore future modifications that file – as developers add additional configuration settings and/or their secrets to it, it’ll get staged. So local.settings.json does need to stay in .gitignore.

@ankitkumarr the defaults from func init produce an environment that works for a developer but will fail on everyone else after checked into Git. If the handful of defaults in local.settings.json are required to build and deploy but that file added to .gitignore by default Git, then consider also producing a local.settings.json.sample file so that can be checked into Git and it’s clear what magic settings need to be in local.settings.json to setup a local instance or publish a deployment after cloning the function.

I’m also running into this. I tried to clone my project from Git and ran func azure functionapp publish <appname>. func azure functionapp publish <appname> --python does seem to work.

However, the lack of a local.settings.json will cause the following error in func start --python:

[2021-11-23T22:41:37.240Z] ImportError: cannot import name 'cygrpc' from 'grpc._cython' (/usr/local/Cellar/azure-functions-core-tools@4/4.0.3971/workers/python/3.8/OSX/X64/grpc/_cython/__init__.py)

To work around this bug, I had to create a local.settings.json with the following content:

{
  "IsEncrypted": false,
  "Values": {
    "FUNCTIONS_WORKER_RUNTIME": "python"
  }
}

Very annoying that people who clone the project will also have to do this.

@apawast I’m not the original author of the issue but per above, definitely still experiencing this.

It would be nice if local.settings.json was safe to gitignore, but today it needs to be checked in or else language detection fails.

Seems you are missing the project loca.settings.json reference in the project configuration level. Check if you see the follwing in the <Project Sdk="Microsoft.NET.Sdk"> xml and add it if missing. I had the same issue. Not sure how I missed (or got removed) it. It worked.

@garrytrinder are you still experiencing this issue?