Fix Office 365 Error 4wbr5 Authentication Cache Corruption

Outlook, Teams, or other Office apps show "Something went wrong" with error tag 4wbr5. This happens when the authentication token cache gets corrupted, often in shared environments like RDS or Azure Virtual Desktop.

The Fix

Close all Office apps (Outlook, Teams, OneDrive, Word, etc.), then clear the auth cache:

# Run in PowerShell
Stop-Process -Name "OUTLOOK","TEAMS","WINWORD","EXCEL","POWERPNT","ONENOTE" -Force -ErrorAction SilentlyContinue

# Move cache folders (safer than delete)
$timestamp = Get-Date -Format "yyyyMMdd-HHmmss"
Rename-Item "$env:LOCALAPPDATA\Microsoft\OneAuth" "OneAuth-backup-$timestamp" -ErrorAction SilentlyContinue
Rename-Item "$env:LOCALAPPDATA\Microsoft\IdentityCache" "IdentityCache-backup-$timestamp" -ErrorAction SilentlyContinue

# Restart Click-to-Run service
Restart-Service -Name "ClickToRunSvc" -Force

Relaunch Outlook and sign in when prompted.

Verify

Office apps should prompt for fresh credentials and work normally after signing in.

If error persists, also clear Windows Credential Manager entries for Office:

Control Panel > Credential Manager > Windows Credentials
Delete entries starting with "MicrosoftOffice" or your email domain

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