Attempting to create users with long usernames (>65 characters) are not handled cleanly in the front-end or back-end

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• Nextcloud Server is running on 64bit capable CPU, PHP and OS.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

[Add new user] The system reported an error, the account was still created successfully

Steps to reproduce

1. Sign in
2. Social Security Profile > Users
3. Add new user
4. Enter Username >65 characters
5. Save

Expected behavior

Add new user failed

Installation method

Community Manual installation with Archive

Nextcloud Server version

25

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.1

Web server

Apache (supported)

Database engine version

MariaDB

Is this bug present after an update or on a fresh install?

Fresh Nextcloud Server install

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

.

List of activated Apps

.

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

No response

Start by reproducing the Add new user flow described in the issue with a username over 65 characters, checking both the front-end response and whether the account is created. Trace the user-creation entry points and existing username-length validation, then verify that the operation reports failure without creating an account.