Sign-in & Login Problems

How to Fix Office 2021 Account Error and Sign-In Loop

Aamir Naveed Akram Sep 28, 2026 869 views

Question details

Users are stuck in a continuous sign-in loop when trying to authenticate Microsoft Office 2021, preventing document synchronization with cloud services.

How to Fix the Office 2021 Account Error and Sign-In Loop

Product: Microsoft Office 2021
Device & OS: Windows
Scenario: Attempting to sign in to Office applications or sync Word and Excel files with Microsoft OneDrive.
Observed behavior: Office 2021 repeatedly prompts the user to sign in, displays an account error message, and fails to synchronize files with OneDrive across multiple accounts.

Before you start

Ensure all Microsoft Office applications (Word, Excel, PowerPoint) are completely closed via the Task Manager and back up any local unsaved work before proceeding.

Solution 1Recommended

Clear Office Authentication Caches

Removing the corrupted cached credentials forces Office 2021 to generate a new authentication token, which typically resolves the sign-in loop.

Windows stores Microsoft Office login tokens in local AppData folders. When these tokens expire or corrupt, Office fails to recognize your account.

Open the Run Dialog

Press the Windows key + R on your keyboard simultaneously to open the Windows Run dialog box.

Clear the OneAuth Folder

Type %localappdata%\Microsoft\OneAuth into the Run box and press Enter. Select all files and folders in this directory and delete them.

Clear the IdentityCache Folder

Press Windows key + R again, type %localappdata%\Microsoft\IdentityCache, and press Enter. Delete all contents within this folder.

Restart and Sign In

Restart your Windows computer. Open Microsoft Word or Excel and follow the prompts to sign in to your Microsoft account again.

Solution 2

Remove Affected Identity Registry Entries

If clearing cache folders does not resolve the account error, you may need to delete corrupted identity profiles directly from the Windows Registry.

Free Microsoft Office alternative

Avoid Sign-In Hassles by Switching to WPS Office

If Microsoft Office 2021 continues to trap you in frustrating sign-in loops and account errors, consider trying a reliable alternative. WPS Office provides a seamless offline and online experience without heavy authentication requirements.

Completely free to download and use for essential daily tasks.Fully compatible with Microsoft Office formats, including .docx, .xlsx, and .pptx.Lightweight architecture that avoids the complex background authentication services of Office 2021.Familiar user interface requiring zero learning curve for seamless migration.

Frequently Asked Questions

Why does Office 2021 keep asking me to sign in?

This recurring prompt is usually caused by outdated or corrupted authentication tokens stored in your local application data. When the Microsoft server cannot validate these local tokens, the software repeatedly asks you to sign in.

Will deleting the OneAuth and IdentityCache folders delete my files?

No. The OneAuth and IdentityCache folders only store temporary login credentials. Deleting them will simply sign you out of Office apps, leaving your Word documents, Excel spreadsheets, and OneDrive files completely untouched.

What should I do if the sign-in loop continues after editing the registry?

If clearing caches and editing the registry fails, you can download the Microsoft Support and Recovery Assistant (SaRA) tool from the official Microsoft website to automatically diagnose and repair Office, or perform a complete reinstall of Office 2021.

Login & Account Issues