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Common problemMicrosoft 365Microsoft 365 desktop apps on Windows and Mac
Can't sign in to Microsoft 365 apps
Often shows Something went wrong [1001]
Word, Excel, Outlook or PowerPoint will not finish signing in on the desktop. Microsoft says security software that interferes with the Windows sign-in component, or tools that copy sign-in data between profiles, can cause this.
How to fix it
Restart your device, which often clears the error for a while.
Install the latest Office updates, since newer versions include fixes for sign-in failures.
Use Outlook on the web, Office on the web or the mobile apps until sign-in works again.
If you use a work or school account and it keeps failing, contact your IT admin.
From Microsoft 365's help pages: support.microsoft.com, in our words. Checked on 5 November 2026. If the steps do not help, Microsoft 365's own support is the next stop.
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