[Identity] Allow Email-Only Authentication Without Mandatory Username Field

[Imorales0210]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

Hello Everyone!

Problem Description

When creating a RESTful API with .NET Core and Identity, the UserManager requires a value for the UserName field even if it is explicitly removed from the user entity. Current community solutions involve:

• Manually setting the UserName to the user’s email (with sanitized characters) or
• Creating a custom UserValidator to bypass the requirement.

While these workarounds function, they feel hacky and counterintuitive for modern authentication flows where email/password is standard and username/password is less common.

Describe the solution you'd like

Expected Behavior
The UserManager should allow developers to configure authentication to use email-only (without requiring UserName). Example:

services.Configure<IdentityOptions>(options => {  
    options.User.RequireUserName = false; // Hypothetical  
});  

Current Behavior
The UserName field is mandatory, forcing developers to implement non-standard workarounds.

Proposed Solution
Add a configuration parameter to IdentityOptions to control whether authentication uses:

• UserName only
• Email only
• Both

This would align with modern authentication patterns and reduce boilerplate code.

Additional context

Research links:

1. https://stackoverflow.com/a/19460800
2. https://stackoverflow.com/a/78826649

Lastly, thanks for your time and if you have a better solution please share it with me.

[halter73]

Is it possible to simply duplicate the email address as the username like we do in the default Identity UI razor pages? Is the bigger issue that you want to be able to login without a password and just use an email confirmation code?

[dotnet-policy-service]

Hi @Imorales0210. We have added the "Needs: Author Feedback" label to this issue, which indicates that we have an open question for you before we can take further action. This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.