Advisory: Az.Accounts 5.5.1 + PnP.PowerShell crash the PS 7.4 worker with MissingMethodException (AddHttpClient/AddOptions)

[andystaples]

Summary

When a PowerShell 7.4 Functions app loads both Az.Accounts 5.5.1 and PnP.PowerShell, any PnP cmdlet that builds an HTTP client (e.g. Connect-PnPOnline) throws a System.MissingMethodException inside PnP.Framework. Downgrading to Az.Accounts 5.5.0 resolves it.

This has been reported by multiple customers. Filing as an advisory so others hitting the same exception can find the cause and workaround, and to flag a possible assembly-isolation issue in the worker.

Exact exception

System.MissingMethodException: Method not found:
  'Microsoft.Extensions.DependencyInjection.IServiceCollection
   Microsoft.Extensions.DependencyInjection.OptionsServiceCollectionExtensions.AddOptions(
     Microsoft.Extensions.DependencyInjection.IServiceCollection)'.
  at Microsoft.Extensions.DependencyInjection.HttpClientFactoryServiceCollectionExtensions.AddHttpClient(IServiceCollection services)
  at Microsoft.Extensions.DependencyInjection.HttpClientFactoryServiceCollectionExtensions.AddHttpClient(IServiceCollection services, String name, Action`1 configureClient)
  at PnP.Framework.Http.PnPHttpClient.AddHttpClients(IServiceCollection collection, String UserAgent)
  at PnP.Framework.Http.PnPHttpClient.BuildServiceFactory()
  at PnP.Framework.Http.PnPHttpClient..ctor()
  ...
  at PnP.PowerShell.Commands.Base.ConnectOnline.ProcessRecord()

Root cause

The two modules ship conflicting Microsoft.Extensions.* assemblies that get co-loaded into the worker process:

Assembly	Source	Version
Microsoft.Extensions.Http	PnP.Framework (bundled with PnP.PowerShell 3.2.0)	8.0.0.0
Microsoft.Extensions.Options	Az.Accounts 5.5.1	10.0.0.0

Microsoft.Extensions.Http 8.0.0.0 was compiled against the AddOptions(IServiceCollection) overload, which is not present in the Microsoft.Extensions.Options 10.0.0.0 that resolves in the worker → MissingMethodException.

Confirmed by changing only the Az.Accounts version (everything else identical):

Az.Accounts	Microsoft.Extensions.Options loaded	Result
5.5.1	10.0.0.0	❌ MissingMethodException
5.5.0	8.0.0.0	✅ works

Reproduction

requirements.psd1:

@{
    'Az.Accounts'    = '5.5.1'
    'Az.Resources'   = '10.0.0'
    'Az.Storage'     = '9.7.0'
    'PnP.PowerShell'  = '3.2.0'
    'Az.KeyVault'    = '6.5.0'
}

In an HTTP-triggered function:

Import-Module Az.Accounts
Import-Module PnP.PowerShell
Connect-PnPOnline -Url 'https://contoso.sharepoint.com' -ClientId '<id>' -ClientSecret '<secret>'
# -> System.MissingMethodException in PnP.Framework.Http.PnPHttpClient.AddHttpClients

Both modules are required to reproduce — Az.Accounts alone does not load Microsoft.Extensions.Http; PnP.Framework supplies the Http 8.0.0.0 assembly and is the caller of AddHttpClient.

Workaround

Pin Az.Accounts to 5.5.0 in requirements.psd1:

'Az.Accounts' = '5.5.0'

Environment

• Functions runtime: 4.1048.200.26180 (Core Tools 4.12.1)
• Worker: PowerShell 7.4.13 (.NET 8)
• FUNCTIONS_WORKER_RUNTIME_VERSION: 7.4
• Managed dependencies enabled