Error in Outlook Web Browser

Question

Hello, I am recieving this error when trying to login to my Outlook on my browser.

BootResult: fail
Back Filled Errors: Unhandled Rejection: SyntaxError: Failed to execute 'json' on 'Response': Unexpected end of JSON input:undefined|Unhandled Rejection: SyntaxError: Failed to execute 'json' on 'Response': Unexpected end of JSON input:undefined|Unhandled Rejection: SyntaxError: Failed to execute 'json' on 'Response': Unexpected end of JSON input:undefined|Unhandled Rejection: Error: 440:undefined|undefined:undefined|undefined:undefined|undefined:undefined|undefined:undefined
err: AccountTerminationException
esrc: StartupData
et: ServerError
estack: Error: 440
    at Object.w [as createStatusErrorMessage] (https://res.public.onecdn.static.microsoft/owamail/hashed-v1/scripts/owa.mailindex.fc02d13f.js:1:1039)
    at https://res.public.onecdn.static.microsoft/owamail/hashed-v1/scripts/owa.mailindex.fc02d13f.js:1:170296
st: 440
ehk: X-OWA-Error
efe: PR1P264CA0147

Answer 1

Thanks for bringing this up. I’m here to help.

I’ve checked, and Outlook services are fully operational, so the issue is likely on the client side, possibly related to your network, security software, or a firewall blocking Microsoft’s authentication process. Let’s go through some steps to resolve this.

Step 1. Clear browser cache and cookies

In Edge/Chrome, press Ctrl+Shift+Del

Clear Cached images and files + Cookies and site data

Close the browser, reopen it, and try again

Step 2. Try in a private/incognito window

Chrome: Ctrl+Shift+N

Edge: Ctrl+Shift+N

If it works there, your stored session is corrupted

Step 3. Test another browser or device

Log in on your phone browser or another PC

If it fails everywhere, it’s the account/server-side

Step 4. Check account status

Go to account.microsoft.com and try to log in there

If you see warnings about security info, password reset, or account suspension, resolve those first

Step 5. Disable VPN, extensions, or switch networks

Temporarily turn off VPN or ad/security extensions in your browser

If possible, try another network, such as a mobile hotspot, to rule out network filtering

For reference, here’s where to check Microsoft service status. You can confirm if there are any reported issues.

https://status.cloud.microsoft/

You may also find more details in this Microsoft article:

Enable or disable user access to Outlook for Windows in Exchange Online

https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/outlook-on-the-web/enable-disable-employee-access-new-outlook

Let me know how it goes.

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Note: Please use the Add a comment section below this message to reply, instead of using the Answer field, so that I’ll be notified of your response.

Answer 2

UPDATE - I found my solution, the trick was the "err: AccountTerminationException" in the error. This is saying that the mailbox account is disabled, not necessarily the user's account. They are separate in 365 land.

Their mailbox accounts, NOT their AzureAD accounts were disabled.   So they were basically like a shared-mailbox.

command to check status:
get-mailbox UPN | fl accountdisabled
command to fix:

Set-Mailbox UPN -AccountDisabled $false

command to find all mailboxes with this setting:
Get-Mailbox -ResultSize Unlimited | Where-Object { $_.AccountDisabled -eq $true }