Microsoft 365 Error Codes

Fix Microsoft 365 Sign-In Error 1200 in Teams and Office Apps

Ayan Masood Oct 7, 2026 869 views

Question details

The user is unable to sign into Microsoft 365 desktop applications such as Teams, Outlook, Word, and Excel due to Error 1200, despite the web versions functioning normally.

How to Fix Microsoft 365 Sign-In Error 1200 in Teams and Office Apps

Product: Microsoft 365
Device & OS: not provided
Scenario: Attempting to log into Microsoft 365 desktop client applications for work or school.
Observed behavior: The application returns Error 1200 and blocks sign-in. This is typically caused by corrupted local credentials or conflicting active accounts on the device.

Before you start

Ensure you save your work and completely close all Microsoft Office applications, including Teams and Outlook, running in the background before modifying credentials.

Solution 1Recommended

Sign Out and Sign Back into Office Applications

A quick manual reset of your active Office session can often resolve immediate authentication glitches causing Error 1200.

Open an Office Application

Launch Microsoft Word or Excel from your desktop or start menu.

Access Account Settings

Click on 'File' in the top-left corner, then select 'Account' from the bottom-left menu pane.

Sign Out

Under the User Information section, click the 'Sign out' button and confirm the prompt.

Sign Back In

Restart the application, click 'Sign in', and enter your Microsoft 365 credentials to activate Office again.

Solution 2

Disconnect Conflicting Work or School Accounts

Conflicting or obsolete accounts linked to your Windows device can cause authentication overlaps leading to Error 1200.

Solution 3

Clear Cached Credentials and Office Identity via Registry

Removing corrupted cached credentials forces Office to request a fresh authentication token directly from Microsoft servers.

Free Microsoft Office alternative

Switch to WPS Office for a Hassle-Free Experience

If Microsoft 365 login errors like Error 1200 keep disrupting your workflow, consider trying WPS Office. It provides a lightweight, highly compatible, and free alternative without the complex login or forced cloud synchronization requirements.

Fully compatible with Microsoft Word, Excel, and PowerPoint formats (.docx, .xlsx, .pptx)No forced cloud sign-ins required to edit, create, and save local documentsLightweight installation that runs smoothly on older and newer PCsFamiliar user interface makes transitioning completely seamless

microsoft office alternative - wps office

Frequently Asked Questions

Why am I getting Error 1200 in desktop apps but not in the browser?

Browser versions of Microsoft 365 use standard web cookies for authentication. Desktop applications, however, rely on Windows Credential Manager and the local registry's Office Identity cache, which can become corrupted or confused by multiple accounts.

Does Error 1200 mean my Microsoft 365 account has been locked?

No. Error 1200 is specifically a local device configuration or caching issue. It simply means your computer's stored login data is conflicting, not that your actual Microsoft account is banned or locked.

Do I need administrative privileges to fix Error 1200?

While signing out of Word or Teams does not require admin rights, clearing system-level Windows credentials and editing the registry to remove the cached Office identity will require administrator access.

Microsoft Office Error Codes