Outlook.com Mailbox Won’t Open (Error 500, BootResult: fail)

Hello,

I am experiencing an issue with my personal Outlook.com account.

I can sign in to my Microsoft account successfully and access https://account.microsoft.com without any problems. However, when I try to open Outlook on the web, the mailbox does not load and I receive a server error.

I have already tried the following troubleshooting steps:

• Tested multiple browsers.
• Used Incognito/InPrivate mode.
• Cleared browser cache and cookies.
• Tested on different devices.
• Tested on different networks.
• Verified that other Outlook accounts open normally on the same devices and browsers.
• The issue affects only this specific account.
• The Outlook mobile app can sign in, but it also appears to have synchronization issues.

The error details are:

UTC Date: 2026-08-31T17:19:05.808Z
Client Id: 9D7C33481A0944358D0105D625C6AF99
Session Id: 960754e5-ab26-4fa1-b100-8d53e736697e
Client Version: 20260821009.09
BootResult: fail
err: Error: 500
esrc: StartupData
et: ServerError
st: 500
efe: SA0PR11CA0159
reqid: cf4cad73-dc62-7db9-c41c-1c31035259df
cv: b/XxksCwFmgDAuQyGgLazX.3.1.1

Since I can authenticate successfully, other Outlook accounts work normally, and the issue appears to be isolated to this mailbox, could you please check whether there is a mailbox provisioning, synchronization, or server-side issue affecting this account and help restore access?

Thank you for your assistance.