I'm trying to use Connect-ExchangeOnline and similar PowerShell tools on macOS 26.4.1, but interactive authentication fails with a System.PlatformNotSupportedException from Microsoft.Identity.Client. Is macOS 26 officially supported yet, and is there a reliable workaround for connecting to Exchange Online?
4 Answers
You can also authenticate through a device code instead of the default interactive browser flow:
`Connect-ExchangeOnline -Device`
This redirects authentication to a browser and can bypass the operating-system version check. However, device-code authentication may be disabled by policy in some organizations, so it isn’t always an acceptable long-term solution.
The prerelease module appears to fix compatibility for some macOS 26 releases, but minor operating-system updates may temporarily break the built-in browser authentication again until Microsoft publishes another compatible module version. If the issue returns, check for a newer ExchangeOnlineManagement prerelease or use the device-code workaround if your tenant permits it.
A practical workaround is to remove the currently installed ExchangeOnlineManagement module and install the prerelease version instead. This resolved the browser authentication error for several people on macOS 26.x:
`Uninstall-Module ExchangeOnlineManagement`
`Install-Module ExchangeOnlineManagement -AllowPrerelease`
You may need to start a new PowerShell session afterward.
This isn’t simply a case of replacing Exchange Online PowerShell with Microsoft Graph. Graph covers many Outlook and mail operations, but Exchange Online administration still uses its own management module and cmdlets. Updating the module or using the device-code flow is more relevant here.
That worked around the error for me, but device-code authentication is blocked in our environment as a security best practice.