Recently my Microsoft Teams Desktop app started showing the error code caad0009 and I was unable to use the Teams app from thereon. This a rare sign-in error which indicates the service could not validate your credentials or recognize your device. Although it occurs quite rarely, this error primarily affects work and school accounts and it only occurs on the Windows Desktop app, i.e. you can still use the Teams browser version, Teams mobile app, or even the Teams Desktop app on a totally different Windows device. I searched quite some time to finally resolve this issue with a simple Powershell command. All other solutions didn’t work for me.

The exact error message states:

Error code – caad0009
There’s a more permanent way to sign in to Microsoft Teams. If you’re having trouble completing the process, talk to your IT admin

Other solutions suggested things like

  • clearing the Windows Credentials cache
  • clearing the Teams Desktop app cache
  • re-installing Teams Desktop app
  • running Teams Desktop app in compatibility mode (e.g. Windows 7)

Someone even suggested that “it was a corrupt MicroSD card I had inserted couple of days a go, which prevented MS Teams and OneDrive from starting or signing in.” Hilarious, really!

It came all down to WAM (web Account Manager) and ADAL (Azure Active Directory Authentication Library). By running this little Powershell command in an elevated Windows Powershell shell the Teams Desktop app started working again like a charm:

if (-not (Get-AppxPackage Microsoft.AAD.BrokerPlugin)) { Add-AppxPackage -Register "$env:windir\SystemApps\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\Appxmanifest.xml" -DisableDevelopmentMode -ForceApplicationShutdown } Get-AppxPackage Microsoft.AAD.BrokerPlugin

In my case the command took almost an hour to complete and it simply stood there with a blinking cursor with nothing seemingly happening. I just kept it that way and all of a sudden it completed successfully. And after that Teams Desktop started working immediately without having to reboot my PC or anything.

Further reading:

Microsoft Teams (Desktop App) Error Code CAAD0009

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