Thank you for reaching Microsoft Q&A Forum!
When you are trying to login to Azure portal using their personal Microsoft Account (Outlook, Hotmail..) they are getting AADSTS160021 or AADSTS16000 or AADSTS50020 errors.
Error AADSTS16000 is thrown when the user not found in the tenant used for authentication. In your case, this error usually occurs when you sign in to Azure Portal using your personal account which is not the part of the tenant or not added as an external/guest user to an Azure AD tenant. Due to this, you by default get connected to the Microsoft Services tenant.
Reason: Whenever you sign in Azure portal using Microsoft Personal Account you by default get connected to the Microsoft Services tenant.
If you are connected to the Microsoft Services tenant as a standard user with restricted access, you cannot perform actions such as creating new users, groups, enterprise applications, and installing Kubernetes. To perform administrative actions, you must have administrative access to the tenant.
Solution: You need to create your own tenant rather than using the Microsoft Services tenant.
You get one with an Azure free trial
When you create a new tenant, you by default become the Global Administrator of the new tenant and have full access to all the options in that tenant.
In some cases, the user might already have an active session that uses a different personal account than the one that's intended to be used. Or they have a session that uses their organization account although they intended to use a personal guest account (or vice versa).
In that scenario, try signing in to the Azure Portal trough a tenant-specific URL using the following format:
https://portal.azure.com/<tenant domain name>
Eg.
https://portal.azure.com/constoso.onmicrosoft.com
Hope this helps. Do let us know if you any further queries by responding in the comments section.
If this answers your query, do click Accept Answer
and Yes
for was this answer helpful. And, if you have any further query do let us know.