Unable to login to outlook

Question

Unable to login to outlook

Sommer Glasgow 0

I keep getting this error code when I try to login to my outlook email:

UTC Date: 2026-07-21T20:37:28.439Z
Client Id: [Moderator note: Personally Identifiable Information removed]
Session Id: [Moderator note: Personally Identifiable Information removed]
Client Version: [Moderator note: Personally Identifiable Information removed]
BootResult: fail
Back Filled Errors: None
err: Error: 440
esrc: StartupData
et: ServerError
estack: Error: 440
    at Object.w [as createStatusErrorMessage] [Moderator note: Personally Identifiable Information removed]
st: 440
efe:[Moderator note: Personally Identifiable Information removed]
reqid:[Moderator note: Personally Identifiable Information removed]
cv: [Moderator note: Personally Identifiable Information removed]

Anonymous

2026-07-22T20:55:02.2766667+00:00

Hi Sommer,

I am following up on the support thread that has been discussed and wanted to check whether you need any further assistance from my side.

If you have additional questions, please feel free to reach out at any time. I would be happy to assist further as needed.

Thank you again for your collaboration.

1 answer

Your answer

Anonymous

2026-07-22T20:55:02.2766667+00:00

Hi Sommer,

I am following up on the support thread that has been discussed and wanted to check whether you need any further assistance from my side.

If you have additional questions, please feel free to reach out at any time. I would be happy to assist further as needed.

Thank you again for your collaboration.

Answer 1

Hi Sommer,

Good day and thank you for taking the time to provide the detailed error information.

Based on the error details you shared, it appears that Outlook on the web is encountering a problem during the sign-in and startup process. While the error code itself does not point to a single confirmed cause, it may be related to an authentication session issue, cached browser data, or an account-side problem that is preventing Outlook from loading successfully.

With this in mind, you may wish to try the following steps:

1/ Sign out of all Microsoft sessions and sign in again

Open your browser and sign out of all Microsoft services.
Close all browser windows completely.
Reopen the browser and sign back in to your account.
Then try accessing Outlook again.

2/ Clear browser cache and cookies

In your browser settings, clear all cached images/files and cookies.
Close the browser after the cleanup is complete.
Open a new browser session and try signing in again.

3/ Test using an InPrivate or Incognito window or a different browser

Open an InPrivate window or different browser, then sign in to Outlook from these browsing windows and check whether the issue persists.

4/ Test from another device or network

Try signing in from a different computer, tablet, or mobile phone.
Alternatively, connect to a different network, such as a mobile hotspot.
This can help identify whether the issue is specific to a particular device or network environment.

5/ Contact your IT admin

Should the issue persist, you may wish to contact your IT administrator for further assistance by reviewing the following areas:

Review sign-in logs for authentication failures.
Verify your license and mailbox status.
Check Conditional Access and security policies to ensure there are no restrictions blocking Outlook on the web access.
Review and, if necessary, reset MFA settings. For reference: Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID |…
Raise a Microsoft support ticket for further investigation from the service side if the issue persists. Get support - Microsoft 365 admin | Microsoft Learn

In case you do not know who your IT admin is, kindly refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support

I hope the information provided helps guide you in the right direction. Please feel free to share any additional details if you need further assistance.

If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in this documentation to enable e-mail notifications if you want to receive the related email notification for this thread.