Outlook.com Mailbox Inaccessible – HTTP 500 StartupData / Repeating Redirects

Hello Microsoft Support,

I have a personal Outlook.com mailbox that is inaccessible through both Outlook Web and Outlook for Android.

My Microsoft account authentication succeeds, and I can access my Microsoft account/profile normally. However, when I try to access Outlook Mail, Outlook Web fails during StartupData with an HTTP 500 ServerError and the message "Repeating redirects detected."

At the same time, Outlook for Android is permanently stuck on "Downloading your messages."

I have already:

• Tested another browser/private browsing session
• Attempted to access Outlook directly
• Reset the affected account in Outlook Android
• Confirmed that my internet connection is working normally
• Confirmed that my other Microsoft email accounts work normally

Because the problem occurs independently on Outlook Web and Outlook Android while Microsoft account authentication works, please investigate this as a possible mailbox/Outlook.com service-side issue rather than a password, browser-cache, or mobile-client issue.

Please check the affected mailbox's OWA/mailbox provisioning, routing, and account/session state, and determine whether the mailbox requires a server-side repair or reset.

Here are the complete error details:

UTC Date: 2026-09-14T09:08:11.620Z

Request ID: c021a00a-b5b2-0634-70b7-b4dab35ba226

Session ID: 8ba7b769-9f3c-4a37-b55a-5c1c3120cf37

Client ID: AE95E0F4ED0D41AB8EA8BF9DC1BAAAAD

Client Version: 20260904006.10

Error: 500

Source: Startup Data

Server Error: 500

BootResult: fail

I can also provide the screenshot of the full error page if required.

Please escalate this to the appropriate Outlook.com/Exchange service team if necessary, as the standard client-side troubleshooting steps have already been completed.

Thank you.