Error 1001 in Windows and Office: what it means and how to fix it

Applies to: Windows 11, Windows 10 and Microsoft 365 desktop apps. If you saw 1001 in Zoom, Roblox, an Adobe updater or on a website, that is a different error from that app or service; check its own help pages.

Which error 1001 do you have?

Match what you saw to one row, then jump to that section.

Where you saw it	What it means	Go to
Event Viewer, Application log, source Windows Error Reporting	A crash or hang report was created or changed state	Event ID 1001
Word, Excel, PowerPoint or Outlook: Something went wrong. [1001]	Office could not sign you in to Microsoft 365	Microsoft 365 [1001]
A setup or uninstall window: Error 1001. followed by an exception	The program’s own installer code failed	Installer Error 1001

Event ID 1001 in Event Viewer

Event ID 1001 from Windows Error Reporting is logged for every problem report Windows makes: application crashes, application hangs and other reports. It is written again each time the report changes state (for example when it is queued or sent), so several 1001 entries for one problem are normal. On its own it is not a fault; it points to one.

Find out what actually failed:

1. Right-click Start, choose Event Viewer and open Windows Logs > Application.
2. Click Filter Current Log on the right, type 1000,1001,1002 in the event ID box and click OK.
3. Open a 1001 entry. Event Name shows the type (for example APPCRASH for a crash or a name starting with AppHang for a hang), and the first parameter (P1) usually names the program.
4. Note the Report Id. The matching Event 1000 (Application Error, a crash) or Event 1002 (Application Hang) at the same time gives the faulting program and module.

For a plainer view of the same history, press Win + R, type perfmon /rel and press Enter to open Reliability Monitor. Click a red X on the day of the problem to see which app stopped working.

What to do next depends on the program it names, not on the 1001 itself:

• One app crashes: update it, then repair or reinstall it. For Store apps, Settings > Apps > Installed apps, the three dots, Advanced options, Repair (more in our Store app repair guide).
• A Windows component such as Explorer crashes, or many apps do: run DISM /Online /Cleanup-Image /RestoreHealth and then sfc /scannow from an elevated Command Prompt (see how to use sfc /scannow).
• The PC restarted with a blue screen: a 1001 entry about a bug check or BlueScreen is only the record of it. Use the stop code it lists and follow Your PC ran into a problem; for a specific code such as 0x1000007E, use that guide.
• Entries with no visible problem: if nothing crashed for you, you can ignore them. A report that only changed state is logged too.

Microsoft 365: Something went wrong [1001]

Microsoft lists this as a known sign-in issue in Excel, Word, Outlook and PowerPoint for Microsoft 365 (and Outlook for Mac). It is linked to the Windows sign-in component that Office uses for work and school accounts (the AAD.BrokerPlugin, also called WAM). Two causes are named: security software getting in the way of that component, and profile tools that roam or reset the user’s local app data.

1. Restart the PC.
2. Update Office: in any Office app open File > Account > Update Options > Update Now. Microsoft says builds from Version 2310 (Current Channel) fix some cases.
3. Open Windows PowerShell as your normal user (not as administrator) and run these two commands, which re-register the sign-in components:

Add-AppxPackage -Register "$env:windir\SystemApps\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\Appxmanifest.xml" -DisableDevelopmentMode -ForceApplicationShutdown
Add-AppxPackage -Register "$env:windir\SystemApps\Microsoft.Windows.CloudExperienceHost_cw5n1h2txyewy\Appxmanifest.xml" -DisableDevelopmentMode -ForceApplicationShutdown

Then open the Office app and sign in again. If you use third-party antivirus or endpoint software, its exclusions or a temporary test without it are the next step; that is a decision for whoever manages the PC. Until it is fixed, Office on the web and the mobile apps still work with the same account.

For IT admins: on roaming or VDI profiles, Microsoft says roaming %localappdata% is not supported and the token folders (for example %localappdata%\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy and %localappdata%\Microsoft\TokenBroker) and related HKCU keys must be excluded. The full list is on Microsoft’s page linked below. If the PC also logs work-account registration errors, see User Device Registration event 304.

Installer: Error 1001 during setup or uninstall

This message comes from a custom step inside the program’s own installer (often one built with Visual Studio), not from Windows Installer itself. The words after Error 1001. matter: Exception occurred while initializing the installation, a FileNotFoundException or a missing assembly tells you the setup code could not run or could not find something.

1. Download a fresh copy of the installer from the vendor and run it again; a damaged or partial download can cause this.
2. Right-click the installer and choose Run as administrator.
3. If the message names the .NET Framework or a System. assembly, check Turn Windows features on or off and make sure the .NET Framework version the program needs is enabled, then restart.
4. If it happens during uninstall, try Repair from Settings > Apps > Installed apps first, then uninstall again.
5. Still failing: send the full message to the program’s vendor. The fault is in their setup package, and only they can fix it.

If you build the installer: Microsoft’s setup team traced a common cause to wrong CustomActionData syntax. Directory values need a closing backslash inside the quotes, for example /target="[TARGETDIR]\", and entries are separated by spaces, not semicolons. A verbose MSI log (msiexec /i setup.msi /l*v log.txt) shows the failing action; search it for value 3.

Related guides

• Your PC ran into a problem and needs to restart: what to do
• How to use sfc /scannow
• The app didn’t start in the required time: how to fix it
• User Device Registration event 304 explained

Official sources:

• Microsoft Support: Error Something went wrong [1001] signing in to Microsoft 365 desktop applications
• Microsoft Learn (archive): Event ID 1001, Windows Error Reporting
• Microsoft Learn (archive): MSI custom action fails with Error 1001