Fix Outlook Error 1001 WAM Broker Auth

Office apps show error 1001 with authentication failures. Repair the WAM broker plugin and clear identity cache.

Office apps show "Something went wrong" with error 1001, or authentication popups keep appearing and failing. This is the Windows Web Account Manager (WAM) broker failing - the component that handles modern auth for Microsoft 365.

The Fix

Method 1: Reboot

A simple restart fixes this about 40% of the time. WAM gets stuck and a reboot clears it.

If Reboot Doesn't Work: Repair WAM Plugin

# Run PowerShell as Administrator

# Repair AAD Broker Plugin (work/school accounts)
if (-not (Get-AppxPackage Microsoft.AAD.BrokerPlugin)) {
    Add-AppxPackage -Register "$env:windir\SystemApps\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\Appxmanifest.xml" -DisableDevelopmentMode -ForceApplicationShutdown
}

# Verify it's registered
Get-AppxPackage Microsoft.AAD.BrokerPlugin

Still Failing? Clear Identity Cache

# Close all Office apps first
Stop-Process -Name "OUTLOOK","TEAMS","WINWORD","EXCEL" -Force -ErrorAction SilentlyContinue

# Clear cache folders
Remove-Item "$env:LOCALAPPDATA\Microsoft\IdentityCache" -Recurse -Force -ErrorAction SilentlyContinue
Remove-Item "$env:LOCALAPPDATA\Microsoft\OneAuth" -Recurse -Force -ErrorAction SilentlyContinue

# Restart and sign in fresh

Verify

Office apps should prompt for credentials and authenticate successfully. Common on VDI environments - if you're running Azure Virtual Desktop or RDS, exclude these cache folders from profile roaming.

Need help with Microsoft 365 issues? Contact Rain City Techworks for IT support across the Seattle-Tacoma area.