PowerShell 7.4: FileNotFoundException for Microsoft.Management.Infrastructure when starting local Functions host

[mmacehardyman]

Version

4.6.0+ab90faafcab539d63cd3d0ce5faf1bca4395fccc (64-bit)
Function Runtime Version: 4.1045.200.25556

Description

Azure Functions Core Tools fails to start the PowerShell worker when using PowerShell 7.4, which is documented as the GA/recommended version. The worker crashes immediately with a FileNotFoundException for Microsoft.Management.Infrastructure assembly, preventing local debugging entirely.

The error occurs during PowerShell worker initialization before any user code runs. Microsoft documentation states PowerShell 7.4 is GA and 7.2 ended support on November 8, 2024, but Core Tools 4.6.0 cannot initialize a PowerShell 7.4 session.

Error:
System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.Management.Infrastructure, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. The system cannot find the file specified.
at System.Reflection.RuntimeAssembly.GetExportedTypes()
at System.Management.Automation.Runspaces.PSSnapInHelpers.GetAssemblyTypes(Assembly assembly, String name)
at System.Management.Automation.Runspaces.InitialSessionState.CreateDefault()
at Microsoft.Azure.Functions.PowerShellWorker.Utility.Utils.NewPwshInstance()
at Microsoft.Azure.Functions.PowerShellWorker.Worker.Main(String[] args)

Additional context:

• PowerShell 7.4 runs fine outside Functions (pwsh -Version shows 7.4.6)
• Microsoft.Management.Infrastructure.dll exists in PowerShell 7.4 installation: C:\Program Files\PowerShell\7\microsoft.management.infrastructure.dll
• The assemblies exist in Core Tools worker directory runtimes subdirectories:
  • C:\Program Files\Microsoft\Azure Functions Core Tools\workers\powershell\7\runtimes\win10-x64\lib\netstandard1.6\Microsoft.Management.Infrastructure.dll
  • C:\Program Files\Microsoft\Azure Functions Core Tools\workers\powershell\7\runtimes\win\lib\netcoreapp3.1\Microsoft.Management.Infrastructure.CimCmdlets.dll
• However, the PowerShell worker cannot locate/load these assemblies during initialization
• Core Tools Constants.cs sets PowerShellWorkerDefaultVersion = "7.4"
• Microsoft documentation states PowerShell 7.2 support ended November 8, 2024
• Using PowerShell 7.2 with FUNCTIONS_WORKER_RUNTIME_VERSION "7.2" works correctly (but is end-of-life)

This creates an impossible situation: Microsoft documentation recommends 7.4, but Core Tools 4.6.0 (the latest version) cannot run PowerShell 7.4 locally on Windows.

Steps to reproduce

1. Environment Setup:

   • Install PowerShell 7.4.6 (only version installed, not 7.5)
   • Install Azure Functions Core Tools 4.6.0
   • Install .NET 8 runtime
   • Windows 10/11 x64

2. Create PowerShell Function App:
   func init --worker-runtime powershell
   func new --template "Timer trigger" --name TimerTrigger1

3. Configure for PowerShell 7.4 in local.settings.json:
   {
   "Values": {
   "FUNCTIONS_WORKER_RUNTIME": "powershell",
   "FUNCTIONS_WORKER_RUNTIME_VERSION": "7.4"
   }
   }

4. Start debugging:
   func host start

Result: Worker crashes with Microsoft.Management.Infrastructure FileNotFoundException
Expected: Worker starts successfully as PowerShell 7.4 is documented as GA/supported

Update

• When I talked to a colleague about it, I asked if he could try it out using the steps to reproduce. In his case, he got it working without errors. So it appears to be some issue locally on my machine. I would still very much would like to know if there's anything I can do to fix this.
• We need to use PowerShell 7.4 as 7.2 is out of support, and we don't want to commit this version into source control. As a workaround, I created an environment variable on my machine where I set the FUNCTIONS_WORKER_RUNTIME_VERSION value to 7.2 and then it also works on my machine.

[KelvinTegelaar]

Same issue here, might be related to the PowerShell 2 deprecation in the latest Windows Update?

[umangsriv]

Hello @mmacehardyman, thanks for raising this issue, I followed the same steps (Core Tools 4.6.0, PowerShell 7.4.6, .NET 8, Windows 10/11) and the timer trigger runs fine in my environment, so this looks environment‑specific. To help narrow it down, could you share more details about your setup? For example:

• Do you have multiple PowerShell versions installed (7.2, 7.4, Windows PowerShell 5.1)?
• Any custom PATH or PSModulePath settings?
• Are you running Core Tools from the default install path or a custom location?
• Do you see extra probing path info if you run func host start --verbose?

Since others can run the same steps without errors, it seems something local may be affecting assembly resolution, more details would help us debug this further.

[microsoft-github-policy-service]

This issue has been automatically marked as stale because it has been marked as requiring author feedback but has not had any activity for 4 days. It will be closed if no further activity occurs within 3 days of this comment.

If you are not the original author (@mmacehardyman) and believe this issue is not stale, please comment with /bot not-stale and I will not close it.