Outlook does not open on the web.

Anonymous
2025-12-17T11:23:59.38+00:00

I get the following error when I open Outlook on the web:

UTC Date: 2025-12-17T11:13:14.423Z
Client Id: --
Session Id: --
Client Version: 20251212003.06
BootResult: fail
Back Filled Errors: None
err: Error: 440
esrc: StartupData
et: ServerError
estack: Error: 440
    at Object.w [as createStatusErrorMessage] (https:/

)
    at https:/
[Moderator note: personal info removed]

st: 440
efe: --
Outlook | Web | Outlook on the web for business | Sign in
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Answer accepted by question author
Alina-Le 6,415 Reputation points Microsoft External Staff Moderator
2025-12-17T14:10:35.5733333+00:00

Hello @Raghavendra Padmanabha

Welcome to Q&A forum!

Based on the information you provided, you are encountering Server Error 440 on Outlook Web.

  • Error Code: 440
  • Type: ServerError

To understand your issue better, could you please confirm:

  • Are you able to use the Outlook desktop app normally, and does this issue only occur on Outlook Web?
  • Additionally, is anyone else in your organization experiencing the same issue?

We need to determine whether this problem is happening organization-wide or only on your account.

While waiting for this issue to be resolved, you can use the Outlook desktop app as a temporary alternative to ensure your work continues smoothly and you don’t miss important emails.

I also checked Microsoft Service Health, and I haven’t seen any reported issues related to this error.

In the meantime, here are some simple troubleshooting steps you can try:

(I see that the AI reply has provided you with steps 1 and 3, but I will add 2 images to help you do it better)

1/ Clear Browser Cache and Cookies
Remove cached data for outlook.office.com or your OWA domain.

User's image

2/ Sign Out and Sign Back In
Fully log out of all Microsoft accounts and restart your browser.

3/ Try a Different Browser or Private Window
This helps rule out cache or extension conflicts.

User's image

Hope my support can help you move forward!

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  1. AI answer

    2025-12-17T11:24:15.58+00:00

    The error you are encountering when trying to open Outlook on the web may be related to issues with the server or your connection settings. Here are a few steps you can take to troubleshoot the problem:

    1. Check Server Status: Ensure that there are no outages or issues with the Outlook service. You can check the Microsoft service status page for any reported problems.
    2. Clear Browser Cache: Sometimes, clearing your browser's cache and cookies can resolve loading issues. Try this and then attempt to access Outlook again.
    3. Try a Different Browser: If the issue persists, try accessing Outlook using a different web browser to see if the problem is browser-specific.
    4. Disable Browser Extensions: Some browser extensions may interfere with Outlook. Disable any extensions and try again.
    5. Check Internet Connection: Ensure that your internet connection is stable and working properly.

    If you continue to experience issues, it may be beneficial to contact your system administrator or Microsoft support for further assistance.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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