How to fix AADSTS900383?

Question

I have a trouble in sign in my account via outlook. how can resolve it?

Answer 1

Hi Leeshay Li

Thank you for reaching out to the Q&A Forum.

Based on my research, this issue usually happens when a corporate firewall or proxy is configured to block access to external organizations (tenants), or if cached data in Outlook is conflicting with these settings. And here are some recommended steps you can try:

Verify access via Outlook on the Web

Go to https://outlook.office.com> attempt to sign in.

• If you cannot sign in here: The restriction is enforced by your network or IT admin.
• If you can sign in here: The issue is local to your Outlook app > try to clear cache

Clear Cached Account Settings: Windows may be holding onto an old "identity" that is triggering the restriction.

• Close Outlook and all Office apps.
• Go to Windows Settings > Accounts > Access work or school > If you see the affected account listed there, click Disconnect.
• Restart your computer > Open Outlook and try to sign in again.

Create a new Outlook Profile

Here is detailed information you can follow: Create an Outlook profile - Microsoft Support

If none of the above steps resolve the issue, please reach out to your IT Administrator and tell them that you are receiving AADSTS900383. This usually requires them to check Cross-Tenant Access settings or Network Proxy/Firewall restrictions that might be blocking external organizations.

I hope this information helps, or if you need any additional information, please don’t hesitate to reach out!

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Answer 2

AADSTS900383 is an authentication error from Microsoft Entra ID (Azure AD) that indicates a sign-in problem when Outlook tries to connect to Microsoft 365.

For Outlook on Windows (for business), use these steps:

1. Run the Microsoft 365 sign-in troubleshooter
   • Use the Microsoft 365 Sign-in troubleshooter to automatically diagnose and fix common sign-in issues for Microsoft 365 apps:
     • Go to the Microsoft 365 Sign-in troubleshooter from this article: Fix authentication issues in Microsoft 365 apps when you try to connect to a Microsoft 365 service and run it on the affected machine.
2. Repair the account and profile for Outlook
   • Sign in to the Outlook account problems page with the affected Office 365 business account:
     • Open: Fix Outlook account problems in Office 365 for business
   • This page can automatically troubleshoot issues such as:
     • Repeated password prompts
     • Cannot create Outlook profile
     • Cannot connect to mailbox or mailbox not found
     • Invalid license or Office cannot verify license
3. Repair the authentication components (WAM plugin)
   • If the issue is with a work or school account on Windows, repair the Microsoft Entra WAM plugin using PowerShell:
     1. Right-click the Windows icon in the taskbar and select Windows PowerShell (Admin).
     2. Approve the UAC prompt.
     3. Run this command for organizational (work) accounts:

                if (-not (Get-AppxPackage Microsoft.AAD.BrokerPlugin)) { Add-AppxPackage -Register "$env:windir\SystemApps\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\Appxmanifest.xml" -DisableDevelopmentMode -ForceApplicationShutdown } Get-AppxPackage Microsoft.AAD.BrokerPlugin
        

     4. When it completes without errors, restart Outlook and try to sign in again.
4. If sign-in still fails
   • If Outlook still cannot sign in and continues to show AADSTS errors, contact the organization’s Microsoft 365/Entra ID administrator. There may be a domain, licensing, or conditional access policy issue preventing sign-in.

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References:

• Fix Outlook account problems in Office 365 for business
• Fix authentication issues in Microsoft 365 apps when you try to connect to a Microsoft 365 service
• Why am I having trouble signing in to Microsoft Teams?
• Microsoft Entra authentication and authorization error codes