Non-ASCII identifiers for usernames (not GUI names)

[Otzie2023]

Currently, usernames can only consist of ASCII characters, but this poses a problem for email login. SMTPUTF8 allows email addresses with non-ASCII characters in the local part that cannot be converted using Punnycode or similar methods.
To protect existing systems, the default behavior for username validation could remain unchanged, and an opt-in option could allow usernames to be non-ASCII-compliant (as well as -bad-name in Linux user management).

My use case:
I want to switch from OneDrive to Nextcloud at my company, and as an IT service provider, I also want to help other companies migrate to Nextcloud, but because of this username restriction, that’s not an option for me right now (we already use email addresses with non-ASCII characters).

Update:

Patch: unicode-benutzernamen.patch

ótzï@test-System-Product-Name:~/Schreibtisch/nextcloud/nextcloud-docker-dev$ docker compose exec nextcloud occ user:add jürgen
Warning: The account ID contains non-ASCII characters. This requires the "allow_unicode_usernames" system config flag and may break external storage, LDAP, federation, clients or apps that expect ASCII-only account IDs.
Enter password: 
Confirm password: 
The account "jürgen" was created successfully
Profiler output available at http://nextcloud.local/index.php/apps/profiler/profiler/db/SNNzx6eW5aQz7mRIeBUO/
ótzï@test-System-Product-Name:~/Schreibtisch/nextcloud/nextcloud-docker-dev$

I've already done a bit of testing and created a patch—it's doable. Here are a few screenshots

[susnux]

The userid is not meant to be human readable, ideally we will switch over to pure UUIDs / snowflakes for the userid.
But that does not mean you cannot use your emails as the login name.

that’s not an option for me right now (we already use email addresses with non-ASCII characters)

What is the problem with this? You can set a UUID as the userid, set the proper displayName to your user's name and use the email as login name. E.g. for local users the email is always considered for login. If you use LDAP then you can configure it to also use the email attribute for login.

[Otzie2023]

@susnux

E.g. for local users the email is always considered for login.

Are EAI addresses also allowed (i.e., non-ASCII characters in the local part)?

If I use an email address as my login credential, are there any other places where the traditional username appears?

It's important to me that users never see any ASCII-only fields anywhere. Therefore, the setting added here is a good way to ensure this. To avoid compatibility issues and confusion, this option has been intentionally hidden.