Fix Office 365 Credential Prompts Issue After Migration

Himanshu Goyal
Himanshu Goyal | Updated On - 08 Mar 2021 |

Read time 5 min

One of the most common issues that Outlook users face when they’re trying to connect to Office 365 mailbox is continually prompt of credentials. And if the user cancels the credentials prompt, they receive an error message.

The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action.

It occurs mostly when the Office 365 migration has been performed and after that, the user is trying to access the cloud account in the Outlook application. It frustrates the user much as he cannot even configure or access the cloud account in the Microsoft Outlook application at all due to this continuous stuck prompt for credentials. One main reason behind this issue can be the settings of Logon network security on the Microsoft Exchange dialog box is not set to Anonymous Authentication. So, how this issue can be resolved? In this article, we will tell you about all the possible methods to solve this error.

Methods to Fix Outlook Credentials Prompt Issue

There are several methods to resolve this issue. Here we have mentioned some of the most effective ways:

  1. One of the simplest things you can do to solve this issue is updating the Office 365 and software to the latest version.
  2. Try to remove and reset your account credentials.
    Go to “Control panel,” select “Credential Manager” and clear any cached credentials.
    Go to Control panel
  3. Change the Registry for Modern Authentication.
    You can create or change the registry key so that Outlook start using the new authentication method for web services, such as EWS and Autodiscover. To do this follow the below steps:

    • Close MS Outlook and start Registry Editor by typing regedit.exe in the Run dialog box.
    • Find the appropriate registry path according to your Outlook version. In outlook 2016, you can find it here:
      Find the appropriate registry path according to your Outlook version
    • Now, click “Edit” in the menu tab and select “New,” and then click “DWORD Value.
      Click on Edit in the menu tab
    • In the DWORD Value type “AlwaysUseMSOAuthForAutoDiscover” and click “Modify.”
    • Now, type 1 in the value data box and click “Ok.” Exit registry editor to finish the process.
  4. Change the “Login network security” settings to “Anonymous Authentication.”
    Note: This method applies to Outlook 2013 (some builds) and earlier versions of MS Outlook.
    • Go to “Control Panel,” locate and select “Mail.” A new wizard will appear on the screen, select “Show Profiles.”
      In Controle Panel locate and select Mail
    • Select the Outlook profile and click Properties, and then select E-mail Accounts.
    • Now, select the desired profile and click change.
      Select the desired profile and click change
    • A new wizard will appear on the screen, click “More Setting” to open the Microsoft Exchange dialog box, and then select the “Security” Tab.
      Open the Microsoft Exchange dialog box and select the Security Tab
    • In the “Login Network Security” list, select “Anonymous Authentication,” and then click “OK.”
    • Now, finish the process by following the instructions and close the Account settings dialog box.
  5. Check the Checkbox “Remember My Credentials
    When you receive the Outlook credentials prompt on the screen while opening MS Outlook, you’ll see that below the credentials field there is a “Remember my credentials” checkbox. Make sure you tick that checkbox so that you don’t face this issue again and again.
    This way MS Outlook will remember your credentials, and you might not face this problem again.
  6. Using a Group Policy
    Sometimes, this error appears due to a wrong Group Policy. You can either enable or disable group policy for your Exchange account.

    • Go to Policies>>Account Settings>>Exchange>>Authentication with Exchange Server.
    • In the Settings section, select the authentication with Exchange Server.
    • You will find multiple group policies for authentication, such as:
      1. Kerberos/NTLM Password Authentication
      2. Kerberos Password Authentication
      3. NTM Password Authentication

    To disable any of these group policies, select Not Configured under the ‘Authentication with Exchange Server’ section.


Facing the “Office 365 Credentials Prompt” continuously can make you uninstall Outlook from your system, or even make you stop using it. So, fixing this issue is crucial as most of the work is done through it. Using the five methods mentioned in the article, you can quickly fix this error. It explained solutions like updating application/platform version, resetting account credentials, modifying Windows Registry, changing login network security settings, editing Group Policy settings, etc.