Skip to main content
日本語 简体中文 繁體中文

Troubleshooting Steps for When You Cannot Connect to Microsoft 365 with Outlook

Questions

In an Access Control environment, I cannot connect to Microsoft 365 with Outlook.
Please tell me how to resolve this.

Answer

Please follow the troubleshooting steps below.
The order of steps to be taken varies depending on the scope of the issue.

  • If the issue occurs for all users: Please try the troubleshooting steps in the order of 0. → 1. → 2. → 3. → 4. → 5.
  • If the issue occurs for some users: Please try the troubleshooting steps in the order of 0. → 5. → 4. → 3. → 2. → 1.

Troubleshooting Step 0. Check for any issues with Microsoft 365 / HENNGE One+

HENNGE One Status Dashboard
How to check the health of Microsoft 365 services

Troubleshooting Step 1. [If occurring after first use or DNS update] Check DNS settings+

Please check if values such as autodiscover are correctly registered in the DNS records of the domain of the user trying to connect.
Especially if there are separate DNS servers for internal and external use, please ensure that the values are correctly registered on both servers.
＜Reference Article＞
"Create DNS records for Microsoft 365 using Windows-based DNS" (External Link)
"How to use the Remote Connectivity Analyzer to troubleshoot single sign-on (SSO) issues" (External Link)

Troubleshooting Step 2. Check URL filtering+

If you are using a URL filtering service, please ensure that communication to Access Control is allowed.
＜Reference Article＞
"FQDN (URL) or IP addresses to allow when using web proxy or web filtering functions"

Troubleshooting Step 3. Verify connection with a newly created user+

Please verify that a connection can be made with a newly created user.
If existing users cannot connect but newly created users can connect without issues, there may be a problem with the internal parameters held by Access Control.
Please contact HENNGE One Technical Support.

Troubleshooting Step 4. Check if Access Control access permission conditions are met+

If you are using Outlook 2016 and Exchange Online is set to WS-Trust authentication, please check if the authentication request communication reaches Access Control with the information of your network's global IP address.
※ WS-Trust authentication logs cannot be checked from the Access Control management screen, so please contact HENNGE One Technical Support.
＜Reference Article＞
"Issue of being repeatedly asked to log in with Outlook 2016"
"Issue of being repeatedly asked to log in with Outlook 2016 - Part 2"
※ This issue may occur even if Exchange Online is set to modern authentication.
"Issue of being repeatedly asked to log in with Outlook 2016 - Part 3"
"Microsoft 365 URLs and IP address ranges" (External Link)

Troubleshooting Step 5. Check Outlook / Windows OS settings+

If you are using Outlook 2013 / 2016, please try the troubleshooting steps in order from the top.

[Troubleshooting Steps]

  1. Disable Outlook add-ons
    Starting Outlook in safe mode can help determine if the issue is caused by add-ons.
    Disable add-ons one by one and check if the issue improves.
    Please refer to the following for how to disable add-ons.
    Disable add-ins in Outlook for Windows
  2. Delete credentials
    1. Click [Start] - [Control Panel].
    2. Click [User Accounts] - [Manage Credentials].
    3. Click and expand the relevant credentials.
    4. Click [Remove from Credential Manager] and delete all credentials containing the following keywords:​ - Credentials containing the keyword [outlook]
    - Credentials containing the keyword [office365]
    - Credentials containing the keyword [onmicrosoft.com]
    - Credentials containing the keyword [MicrosoftOffice1x ～ SSPI]
    - Credentials containing the keyword [ADAL]
    - Credentials containing the keyword [Autodiscover]
  3. For Windows 10, disconnect the Microsoft 365 account connected to the device
    1. Click the [Start] button and then click [Settings].
    2. In the [Windows Settings] screen, click [Accounts].
    3. Click [Access work or school] on the left side of the screen.
    4. If a Microsoft 365 account is displayed and connected on this screen, click the account and select "Disconnect"
  4. Recreate the Outlook profile, including deleting the OST file
  5. Reinstall the Outlook app
  6. Use the Recovery Assistant Tool
    About Microsoft Support/Recovery Assistant