Microsoft 365 Apps Closing Immediately After Sign-in

When Microsoft 365 applications like Word, Excel, or Outlook close instantly after completing sign-in, a corrupted authentication token or corrupted Web Account Manager (WAM) identity state is terminating the application process. Instead of loading the user workspace, the app encounters a fatal access violation during background license validation and crashes silently to the desktop without an error code. This behavior prevents users from accessing local Office suites even though cloud web services remain functional.

Fast-Fix: The 45-Second Solution

Microsoft 365 apps close immediately after sign-in when corrupted identity tokens in the Windows Web Account Manager cause an unhandled process termination during license verification. Risk Tier: Moderate. To fix this, open Settings > Accounts > Access work or school, disconnect the affected account, clear stale credentials in Windows Credential Manager, and sign back in.

Diagnostic Snapshot

• Severity Tier: Moderate (Blocks local desktop app usage entirely; web versions of Office remain active).
• Data Safety Risk: Minimal (Documents, emails, and cloud storage files remain untouched on local drives and SharePoint).
• Common Cause: Corrupted OAuth identity tokens, broken Workplace Join (WPJ) device registration, or faulted mso20win32client.dll module calls.
• Admin Requirement: User-level access for account disconnects and credential clears; Local Administrator rights required for registry key cleanups or system repairs.

Condition: Low Risk vs. High Risk

• Low Risk: The instant crash happens on a single standalone PC after a password change or Windows update, while logging into Microsoft 365 via a web browser works normally.
• High Risk: The crash occurs across every desktop app on an enterprise-managed computer, recurs immediately after reinstalling Office, or accompanies tenant device registration blocks across multiple workstations.

Common Misdiagnoses

• Misdiagnosed as Application File Corruption: Technicians frequently reinstall Office immediately. However, re-installing rarely fixes this issue because the corrupt identity files reside in the user profile directory (%LocalAppData%), which survives standard uninstalls.
• Misdiagnosed as an Expired Subscription: If your account license were expired, Office would open in Reduced Functionality Mode with a red banner rather than crashing instantly.
• Misdiagnosed as a Modern Auth Failure: While Modern Authentication issues can freeze sign-in boxes, a complete process crash points specifically to a broken token broker handoff. For general Modern Auth troubleshooting, review [INTERNAL LINK: S01C01.12 – How to Resolve Modern Authentication (ADAL/MSAL) Failures in 2025].

Immediate Action Steps

Step 1: Disconnect and Reconnect the Work or School Account

Resetting the OS-level account link clears broken Workplace Join tokens without deleting local files.

1. Close all Microsoft 365 apps.
2. Press Windows Key + I to open Settings.
3. Go to Accounts > Access work or school.
4. Select your corporate or school account and click Disconnect.
5. Restart your computer.
6. Return to Access work or school, click Connect, and re-enter your Microsoft 365 credentials.
7. Launch Word or Excel to verify that sign-in completes cleanly without closing the app.

Step 2: Clear the Local Identity Cache Folders

Removing cached token files forces Windows and Office to generate fresh authentication data.

1. Press Ctrl + Shift + Esc to open Task Manager and terminate any active WINWORD.EXE, EXCEL.EXE, or OfficeClickToRun.exe tasks.
2. Press Windows Key + R, type %LocalAppData%\Microsoft and press Enter.
3. Locate the IdentityCache folder, right-click it, and select Delete.
4. Press Windows Key + R, type %LocalAppData%\Packages and press Enter.
5. Locate the folder Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy.
6. Rename this folder to Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy.old. (If file lock errors occur, log out of Windows and log back in before renaming).
7. If identity broker errors persist, re-register the broker package using the steps in [INTERNAL LINK: S01C01.10 – Resolving “Something Went Wrong” Error 1001 in Outlook and Teams].

Step 3: Remove Stale Credentials from Windows Vault

1. Press Windows Key + S, search for Credential Manager, and open it.
2. Select Windows Credentials.
3. Expand and remove all entries under Generic Credentials that start with MicrosoftOffice16_Data, ADAL, or SSO_POP.
4. For step-by-step instructions on clearing these vaults safely, see [INTERNAL LINK: S01C01.05 – How to Clear Office Credential Cache on Windows 11 (The Modern Way)].

Step 4: Reset the Microsoft 365 Activation State

If clearing local caches does not stop the crashing loop, reset the activation registry state completely following [INTERNAL LINK: S01C01.24 – How to Reset the Microsoft 365 Activation State (Using SaRA Tool)].

Hard-Stop Red Flags

• Faulting Module in Event Viewer: If Windows Event Viewer (Application log, Event ID 1000) lists ntdll.dll or kernelbase.dll as the faulting module instead of mso20win32client.dll, system-level OS corruption is present. Run sfc /scannow in an elevated command prompt.
• Device Disablement Warnings: If the sign-in attempt brief display includes “Your organization has disabled this device,” the device account was revoked in Entra ID. Refer to [INTERNAL LINK: S01C01.06 – Fix: “Your Organization Has Disabled This Device” (Error Code 135011)].
• TPM Hardware Failures: If Event Viewer shows Trusted Platform Module crypto errors during sign-in, consult [INTERNAL LINK: S01C01.03 – Troubleshooting TPM 2.0 Errors (80090016) during Office Sign-in].

What the IT Admin Will Check

1. Entra ID Device Registration: Verify in the Entra ID portal that the user’s device state is marked as Enabled and compliant under Conditional Access policies.
2. Process Crash Dumps: Check %LocalAppData%\CrashDumps for WINWORD.EXE.dmp files to confirm whether the process crash is caused by mso20win32client.dll memory access violations.
3. Group Policy Restrictions: Ensure that Group Policy is not blocking user-level writing to %LocalAppData%\Packages or disabling the Web Account Manager service.

Resolution Complexity

• Moderate: Resolving instant crashes requires removing work accounts from Windows Settings, clearing hidden profile folders in AppData, and removing generic credentials.

Related Error Escalators

• If Office apps open successfully but refuse to activate due to permission blocks, see [INTERNAL LINK: S01C01.34 – How to Fix “0x80070005” Access Denied Activation Error].
• If apps remain open but show an unlicensed product banner, review [INTERNAL LINK: S01C01.01 – Fix: “Account Unlicensed” Error despite active M365 Subscription].

Ticket Closed

When Microsoft 365 applications crash instantly after sign-in, the cause is a corrupted local identity token or broken broker handoff rather than a damaged Office installation. Disconnecting the work account in Windows Settings, clearing the IdentityCache folder, and removing stale generic credentials from Credential Manager fixes the crash sequence. Re-launching any Office app allows a fresh authentication exchange to establish a stable desktop workspace.