Hi Konstantine,
This error Your organization's policies prevent you from changing your primary username occurs when your Windows device or browser session is linked to a Work or School Azure AD / Entra ID organization account, or when the email you are trying to change is tied to an organization tenant rather than a purely personal Microsoft Account (MSA).
Here is how you can resolve this and set your alias as primary:
- Disconnect any Work or School Accounts on Windows: Press Windows Key + I to open Settings. Go to Accounts > Access work or school. Look for any connected school or corporate accounts. If listed, click on it and select Disconnect note: ensure you have your login credentials if you need to re-add it later for school/work access. Restart your PC.
- Manage Aliases in an InPrivate / Incognito Window: Cached organizational single-sign-on (SSO) tokens in your browser often trigger this policy lock. Open a fresh InPrivate / Incognito window in Edge or Chrome. Go directly to: https://account.live.com/names/manage Sign in using your current primary Microsoft account credentials.
- Set Your New Alias as Primary: Under the "Account aliases" section, verify that the new alias email is listed. If not, click "Add email" and complete the verification. Click "Make primary" next to the alias you want as your main username. Once it shows as Primary, you can safely click "Remove" next to the old email address.
Note: If the account you are using was originally issued directly by a university, school, or employer (Microsoft 365 tenant), administrative policies managed by the tenant admin will prevent self-service alias changes. In that case, you must contact your organization's IT helpdesk to update your User Principal Name (UPN).
Let us know if this helps or if you run into any specific prompt along the way!