Possible to rename a group to the same name as an existing group

⚠️ 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

[Edit user group] Rename group with the same name already on the system is still possible

Steps to reproduce

1. Sign in
2. Social Security Profile > Users
3. Rename the user group (Rename the same as the group name already on the system)

Expected behavior

Displays a message that the group name already exists on the system

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

No file or test is named in the report. Start by reproducing the rename flow under Social Security Profile > Users with two existing groups, then trace the user-group rename entry point and its validation. Done means attempting a duplicate name is rejected with a message that the group already exists, while distinct names still work.