Windows security pop up with credentials keeps showing up

Question

Windows security pop up with credentials pops up a lot and I cannot retrieve emails for the past 3h.

Answer 1

Hi Iuliana Zah, 

Welcome to Microsoft Q&A Forum! Have a good day and I hope you're doing well!

I completely understand how frustrating it is to have the Windows Security pop-up appearing constantly, I will do my best to help you resolve it. 

Based on my research, please follow the troubleshooting steps below to identify the cause: 

Step 1: Check your account on Outlook Web App (OWA): First, we need to verify if the issue is with your account/server or just the Outlook application on your computer. 

Sign in with the same email address and password.  

• If OWA works normally: The issue is likely with the Outlook client on your desktop. Please proceed to Step 2. 
• If you cannot sign in to OWA: This indicates an account or password issue. You may need to contact your IT admin to check your account status. 

Step 2: Start Outlook in Safe Mode: This helps determine if an add-in is causing conflicts. 

1. Press the Windows key + R on your keyboard to open the Run dialog. 
2. Type outlook /safe and press Enter. 
3. Check if the pop-up still appears. 

Step 3: Clear old credentials: If the issue persists, Windows might be holding onto an old or corrupted password. 

1. Close Outlook. 
2. Go to Control Panel > Credential Manager > Windows Credentials. 
3. Look for any entries containing "Outlook" or "MicrosoftOffice". 
4. Expand them and select Remove. 
5. Restart Outlook and enter your password one more time when prompted. 

Step 4: Create a new Outlook Profile: If the steps above do not work, your current profile might be corrupted. 

1. Go to Control Panel > Mail. 
2. Click Show Profiles > Add. 
3. Create a new name for the profile and follow the prompts to sign in again. 

Reference: Create an Outlook profile

If the issue still persists, please reply to the Private Message I sent you earlier with more details, such as: 

• Your specific Outlook version (File > Office Account > About Outlook). 
• The type of account you are using (e.g., Microsoft 365 Business, Exchange, or IMAP). 

This information will allow me to gain more insights for further troubleshooting steps or provide you with the appropriate redirects if necessary. 

Please let me know if any of these steps work for you. 

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Answer 2

Follow these steps to stop the repeated Windows Security credential prompts in Outlook and restore mail flow:

1. Remove cached/incorrect credentials
   1. Open Control Panel.
   2. Go to User Accounts > Credential Manager > Windows Credentials.
   3. Look for entries related to Outlook, MicrosoftOffice15_Data:SSPI, MicrosoftOffice16_Data:SSPI, or your Microsoft 365/Exchange account.
   4. Select each related entry and choose Remove.
   5. Close Credential Manager.
   6. Restart Outlook and enter the correct credentials when prompted.
2. Check Outlook’s authentication setting (for Microsoft 365/Exchange)
   1. In Outlook, open Control Panel > Mail > Email Accounts.
   2. Select the affected profile/account and open Change > More Settings.
   3. On the Security tab, ensure Logon network security is set to Anonymous Authentication (for Microsoft 365 scenarios where required).
   4. Save and restart Outlook.
3. If your organization recently changed from RPC over HTTP to MAPI over HTTP If the issue started after a protocol change on the Exchange side, cached RPC-over-HTTP credentials can cause repeated prompts:
   1. Again open Control Panel > User Accounts > Credential Manager > Windows Credentials.
   2. Remove all entries that start with MicrosoftOffice15_Data:SSPI or MicrosoftOffice16_Data:SSPI.
   3. Restart Outlook.
   4. When prompted, sign in using the format domain\user if required by your environment.
4. Update Outlook If this started after a password change or recently and persists across reboots, install the latest Outlook/Office updates, as older builds have known issues with stored credentials and prompts.
5. If still unable to retrieve email
   • Try Outlook on the web (OWA) to confirm the mailbox itself is working.
   • If federated sign-in (AD FS) is used in the organization and all users see repeated prompts, contact the admin to check AD FS and certificate health.

If mail still has not synced for several hours after these steps, involve the Microsoft 365/Exchange administrator to review authentication policies, certificates, and any recent changes in the environment.

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References:

• Outlook continues to prompt for credentials after your domain password changes
• Outlook continually prompts for your password when you try to connect to Microsoft 365
• Outlook repeatedly prompts for credentials when using MAPI over HTTP to connect to Exchange
• Connection issues when signing in after updating to Office 2016 build 16.0.7967 on Windows 10
• Do you know how to fix the issue where Outlook keeps prompting for a password even though credentials are saved - Microsoft Q&A
• Outlook ask for credentials every minute - Microsoft Q&A