PAC CLI 2.8.1 crashes with System.NullReferenceException during `pac auth create` on macOS 26.5.1

Summary

Power Platform CLI installs successfully and all non-authentication commands work. However, every authentication-related command crashes with a System.NullReferenceException before the authentication flow starts.

This prevents authentication and blocks Power Platform Code Apps development on macOS.

Environment

Operating System: macOS 26.5.1 (Build 25F80)
Architecture: Apple Silicon (arm64)
.NET SDK: 10.0.301
.NET Runtime: 10.0.9
Power Platform CLI: 2.8.1

Installation Method:

dotnet tool install --global Microsoft.PowerApps.CLI.Tool

Steps to Reproduce

Install .NET SDK 10.
Install the latest Power Platform CLI:

dotnet tool install --global Microsoft.PowerApps.CLI.Tool

Verify the CLI is installed:

pac

Execute any authentication command:

pac auth create

pac auth create --deviceCode

pac auth list

Expected Behavior

The CLI should start the authentication flow by opening a browser or displaying a device code, allowing the user to authenticate successfully.

Actual Behavior

The CLI immediately terminates with:

Sorry, the app encountered a non-recoverable error and will need to terminate.

Exception Type:
System.NullReferenceException

The authentication flow never starts.

Diagnostic Log

The log shows that the CLI attempts to create an operating system authentication profile before starting authentication:

TryCreateAuthProfileFromOperatingSystemAsync

It then crashes inside the Microsoft Authentication Library (MSAL):

Microsoft.Identity.Client.Platforms.Features.RuntimeBroker.RuntimeBroker

System.NullReferenceException

The stack trace indicates the exception originates from the RuntimeBroker initialization:

Microsoft.Identity.Client.Platforms.Features.RuntimeBroker.RuntimeBroker..ctor(...)
Microsoft.Identity.Client.Broker.BrokerExtension.AddRuntimeSupport(...)
Microsoft.Identity.Client.PlatformsCommon.Shared.AbstractPlatformProxy.CreateBroker(...)

The crash occurs before browser authentication or device code authentication begins.

Additional Information

pac starts successfully.
pac help works correctly.
The issue occurs with:
- pac auth create
- pac auth create --deviceCode
- pac auth list
A clean reinstall of:
- .NET SDK
- Power Platform CLI
- VS Code
  does not resolve the issue.
The issue reproduces consistently.

Impact

This issue prevents authentication to Power Platform environments and blocks development using Power Platform CLI and Power Platform Code Apps on macOS.

Question

Is this a known compatibility issue between PAC CLI 2.8.1 / MSAL RuntimeBroker and macOS 26.5.1?

If so:

Is there a recommended workaround?
Is there a newer CLI build or hotfix that resolves this issue?
Is there a way to disable RuntimeBroker initialization so that browser or device code authentication can proceed?