Sign-in & Login Problems

How to Fix Microsoft 365 Desktop Apps Sign-in Issues on One Computer

Khadija Khan Sep 28, 2026 869 views

Question details

The user is unable to sign in to Microsoft 365 desktop applications on a specific computer, experiencing repeated sign-in prompts and synchronization errors.

How to Fix Microsoft 365 Sign-In Issues on One Computer

Product: Microsoft 365
Device & OS: not provided
Scenario: Attempting to use Microsoft 365 desktop apps after signing up for Copilot Plus.
Observed behavior: The apps repeatedly request the user to sign in and report synchronization problems on one specific computer, despite working correctly on other devices.

Before you start

Verify that your computer is connected to a stable internet network and temporarily disable any active VPNs or proxies that might interfere with Microsoft's authentication servers.

Solution 1Recommended

Clear the Office Identity Cache

Removing cached authentication files is the most effective way to resolve persistent sign-in loops.

Close all Office applications

Ensure that Word, Excel, PowerPoint, and any other Microsoft 365 applications are completely closed.

Access the Microsoft AppData folder

Press the Windows key + R to open the Run dialog. Type %localappdata%\Microsoft and press Enter.

Delete cached credential folders

Locate the folders named 'OneAuth' and 'IdentityCache'. Right-click each folder and select Delete.

Restart and sign in

Restart your computer, open a Microsoft 365 application, and attempt to sign in again.

Safe Deletion: Deleting the OneAuth and IdentityCache folders will not remove any of your personal documents or application settings.

Solution 2

Reset the Office Identity in Registry Editor

If clearing cache folders does not work, clearing corrupted identity registry entries can force a fresh authentication state.

Solution 3

Reinstall Using the Offline Installer

A clean installation using the offline installer can bypass network bugs and fix deep-rooted application errors.

Free Microsoft Office alternative

Avoid Sign-In Loops with WPS Office

If Microsoft 365 continues to experience synchronization and authentication errors, consider switching to WPS Office. It provides a highly compatible and free alternative without mandatory cloud synchronization hurdles.

1. Download the software: Visit the official WPS website and download the free WPS Office installer.
2. Install the application: Run the setup file and complete the fast, one-click installation process.
3. Open your files: Double-click any existing Word, Excel, or PowerPoint document to open and edit it instantly in WPS Office.

Fully compatible with Microsoft Office formats including DOCX, XLSX, and PPTX.Operates efficiently offline without frustrating sign-in loops or sync errors.Lightweight installation that consumes minimal system resources.Familiar interface allowing for seamless migration and immediate productivity.

microsoft office alternative - wps office

Frequently Asked Questions

Why does Microsoft 365 only ask for sign-in on one computer?

This typically occurs when the local authentication tokens or registry keys on that specific device become corrupted. Because the issue is local to the device's cache, your account continues to work normally on other computers.

Will I lose my files if I delete the IdentityCache folder?

No. The IdentityCache and OneAuth folders only store temporary login data. Deleting them forces Microsoft 365 to generate fresh authentication tokens and does not affect your local documents or OneDrive files.

How do I revert to an earlier supported Office build?

Reverting to a previous build usually requires using the Office Deployment Tool (ODT) and executing specific commands in the Command Prompt to target an older version number. This is recommended if a recent update triggered the sign-in bug.

Login & Account Issues