Something went wrong, you may need to make an app password (New Outlook)

Question

This started almost a year ago after moving my email host. I use <PII removed>@mydomaindotnet as my main email account. I have full control over my own email config and its a custom domain I've had the past 18 years, and I most certaintly do NOT have 2FA enabled or an app password. I have tried enabling 2fa with an app password and that does not change anything.

This issue ONLY occurs on Windows 10 & 11 with New outlook. Does not happen with Outlook on Mac, iPhone, or Android. It also works just fine with Outlook 2024 (old outlook)

If I create another email <PII removed>@mydomaindotnet with the same login info, server info etc new outlook on windows works fine. But I cannot use <PII removed>@mydomaindotnet with it.

Even with a Fresh install of Windows 10 or 11 same issue but only with NEW outlook not old outlook.

Need this looked into as this is not an issue on my end.

Thank you.

Answer 1

Please note that our forum is a public platform, and I modified your question to hide your personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data. 

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Hi HPad,

I understand that only one custom-domain mailbox fails in new Outlook for Windows, while the same mailbox works in classic Outlook and on other platforms. Another mailbox on the same mail server also works correctly in new Outlook.

Please note that this is a user-to-user forum, so contributors cannot inspect the account’s authentication records or new Outlook diagnostic logs.

The message does not necessarily mean that an app password is required. Microsoft previously documented the same message for some third-party accounts, but that incident was marked fixed on June 18, 2025. See the documented Outlook incident

Because the behavior follows one mailbox across clean Windows installations, please first compare the affected and working mailboxes at the hosting level, including whether the account uses IMAP or POP, the full username, authentication method, and any mailbox-specific connection restrictions.

If those settings are identical, report the behavior from new Outlook through Help > Support and include:

• The new Outlook version from Settings > General > About Outlook
• Whether the account is configured through IMAP or POP
• The approximate time of the latest unsuccessful setup attempt
• Confirmation that another mailbox on the same server works
• Confirmation that the affected mailbox works in classic Outlook and other Outlook apps

Until the account-specific behavior can be examined, continuing to use classic Outlook for this mailbox is the practical workaround.

I hope these details help ensure the issue reaches the appropriate Outlook support channel with the necessary diagnostic information.