First determine whether the add-in is at fault or the Office app itself is unstable. On Windows, starting the app in Safe Mode provides a useful split: if it runs normally there, an add-in is a plausible cause; if it still will not start, Microsoft says the problem is not with add-ins. Disable extensions temporarily and re-enable them one at a time before considering updates or Office repair.
First identify the app and add-in
The right steps depend on whether you use classic Outlook, new Outlook, Word, Excel, PowerPoint, Office on the web, or a Mac or mobile device. Also note the add-in’s name, the exact error, when the issue began, and whether the Office app closes or only the add-in fails to load.
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Classic Outlook and some Windows desktop apps support COM add-ins. Office Add-ins, by contrast, are web applications that run inside platform-specific browser components. Do not apply classic Outlook COM add-in instructions to new Outlook: Microsoft explicitly says those steps do not apply to it. See Microsoft’s classic Outlook troubleshooting guidance.
Use Safe Mode to test whether add-ins are involved
Safe Mode starts an Office app with certain features, including add-ins, unavailable. It is a diagnostic test, not a permanent fix. If the app is stable in Safe Mode, an add-in may be responsible. If it still crashes or cannot start, follow Office-app troubleshooting instead of focusing on add-ins. Microsoft’s guidance places updates and app troubleshooting among the next steps; Safe Mode does not identify which add-in is responsible by itself.
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Classic Outlook on Windows
- Close Outlook. Press Windows key + R, enter
Outlook /safe, and press Enter. Choose a profile if prompted. - If Outlook behaves normally, close it and open it normally. Go to File > Options > Add-ins.
- At the bottom, set Manage to COM Add-ins and select Go. Clear the checkboxes for active add-ins, then select OK.
- Restart Outlook. If it is stable, return to the COM Add-ins list, enable one add-in, restart Outlook, and test. Repeat until the problem returns; the last add-in enabled is the likely trigger.
Disable add-ins for this test rather than choosing a removal option. Microsoft warns that removal may delete an add-in when you only intend to turn it off. These classic Outlook steps are not for new Outlook.
Word, Excel, and PowerPoint on Windows
- Close the app. Press Windows key + R, enter the relevant command—
winword /safe,excel /safe, orpowerpnt /safe—and press Enter. - If the app works in Safe Mode, open it normally and choose File > Options > Add-ins.
- Use the Manage list to select the relevant add-in type, such as an application add-in or COM Add-ins, and select Go if shown. Disable an add-in, restart the app, and test.
- Re-enable and test add-ins one at a time, restarting after each change, until the failure recurs.
Available add-in types and controls vary by app. For Microsoft’s broader startup troubleshooting, see “I get a ‘stopped working’ error when I start Office applications on my PC.”
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Check whether an add-in is disabled, missing, or blocked
Look for disabled or missing add-ins
In Word, Excel, and PowerPoint, File > Get Add-ins or Home > Add-ins opens add-in management. If an add-in is missing from My Add-ins, use its Refresh option. Microsoft defines “Disabled Application Add-ins” as add-ins automatically disabled because they cause Microsoft 365 programs to crash. Its guide to viewing, managing, and installing add-ins covers the applicable controls.
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Check trust settings only if available
In Windows desktop apps, the path is File > Options > Trust Center > Trust Center Settings > Add-ins. The relevant controls may not be available in every app or installation. A publisher signature that is not trusted can prevent an add-in from loading. Your organization may manage these settings, so do not try to bypass a policy or change controls you are not authorized to manage.
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For a work or school device, involve IT
Some add-ins may conflict with organizational IT policies. Microsoft says policy-incompatible add-ins may be disabled by Data Execution Prevention (DEP), and this can crash the Office program. When reporting the issue, give IT the add-in name, Office app and build, exact error, approximate crash time, whether Safe Mode works, and relevant Event Viewer error details. Microsoft’s add-in management guidance also notes that administrators may control trust settings.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Update Office, then consider repair
Install available Office updates before moving to repair. In an Office app on Windows, use File > Account > Update Options > Update Now where that option is available. If the problem persists after you have isolated add-ins, Microsoft lists app repair among the next troubleshooting steps. Repair options and paths vary by app and platform; for Outlook, Microsoft describes Online Repair, while its broader Office guidance describes trying Quick Repair and then Online Repair. Repair may address an Office installation problem, but it is not a guaranteed add-in fix.
See Microsoft’s Outlook troubleshooting guidance and its Office startup guidance for the applicable instructions.
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Office Add-ins are web applications, and the embedded browser component differs by platform: Windows desktop clients use Microsoft Edge WebView2, Mac and iOS use Safari WKWebView, and Android uses Chrome. Office on the web uses the browser opened by the user. A problem affecting one client but not another may therefore point to a platform-specific runtime or managed-device condition rather than a COM add-in.
Microsoft documents a specific Windows scenario involving a document protected by Windows Information Protection (WIP): for an add-in using WebView2 in that scenario, an administrator must include msedgewebview2.exe in the WIP protected-apps policy. This is an administrator-managed policy adjustment, not a general remedy for add-ins that fail to load. Microsoft says WebView2 is installed with supported Office versions by default; its guidance does not establish reinstalling WebView2 as a universal fix. See Microsoft’s documentation on browsers used by Office web add-ins.
A dated classic Outlook and Teams add-in incident
Microsoft documented a specific classic Outlook crash involving older Office builds and Microsoft Teams Meeting Add-in build 1.26.02603. The issue began around March 12, 2026; Microsoft’s Current Channel example identifies Outlook Version 2402, Build 17328.20142, or lower. Its article marks the issue fixed and says Teams-side fix deployment began March 30, 2026. Microsoft recommends updating classic Outlook. For users who must remain on an older Office build, the documented temporary workaround is to disable Microsoft Teams Meeting Add-in for Microsoft Office. These identifiers describe that incident, not a general cause of current Outlook crashes; check Microsoft’s incident and troubleshooting page for its current status.
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