Microsoft 365 Error Codes

How to Fix Microsoft 365 Sign-In Error 50058 on macOS

Steve K Oct 9, 2026 869 views

Question details

The user is unable to sign in to Microsoft 365 Family apps on macOS and encounters an error stating the username is incorrect.

How to Fix Microsoft 365 Family Sign-In Error 50058 on macOS

Product: Microsoft 365 Family
Device & OS: macOS
Scenario: Signing into Microsoft 365 Family desktop apps on a Mac after receiving and accepting a family subscription invitation.
Observed behavior: The application displays 'This username may be incorrect' alongside error code 50058, even though the Microsoft account is valid and exists.

Before you start

Make sure your Mac is connected to a stable internet network and that you have access to a web browser to manage your Microsoft account settings.

Solution 1Recommended

Add a New Primary Email Alias

Creating a new Outlook email alias and setting it as the primary alias for your Microsoft account bypasses the authentication conflict causing error 50058.

Error 50058 often indicates a session authentication glitch where the Microsoft login server temporarily fails to recognize the original username associated with the family invitation. By assigning a fresh Outlook alias as the primary identifier, you force the system to establish a new, clean login session.

Visit the Microsoft Alias Page

Open your preferred web browser and navigate to the official Microsoft account alias management page.

Add a New Email

Create an Outlook Address

Select the option to create a new Outlook email address and add it as an alias to your existing Microsoft account.

Make it the Primary Alias

Locate the newly created Outlook alias in your list of emails and click 'Make primary' next to it.

Sign In to Microsoft 365

Launch the Microsoft 365 apps on your Mac and sign in using the new primary Outlook alias you just created.

Data Safety: Changing your primary alias does not delete your old email, files, or subscription details. Your data remains completely safe and accessible.

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Try WPS Office for Mac When Microsoft 365 Won't Sign In

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1. Download WPS Office: Visit the official WPS Office website and download the macOS version.
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Frequently Asked Questions

What exactly does Microsoft error code 50058 mean?

Error 50058 typically indicates a session or authentication issue where the server fails to properly identify the user's login credentials. It often happens when multiple accounts are cached or when there is a mismatch during a family invitation acceptance.

Will I lose my original email address if I make a new alias primary?

No. Your original email address will remain attached to your Microsoft account as a secondary alias. You will still be able to receive emails sent to that original address without any interruption.

Can I switch my primary alias back to the original email later?

Yes. Once you have successfully logged into the Microsoft 365 apps and resolved the error, you can return to the Microsoft alias page at any time to set your original email address back as the primary alias.

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