PHP Warning: Undefined array key 0 in Has_Multiple_Admins.php line 93 (multisite

This looks like a real plugin-side edge case, not a normal site configuration issue.

The key point is that ! empty( $super_admins ) only proves the array has values. It does not prove index 0 exists. On multisite, if get_super_admins() returns a keyed or sparse array, $super_admins[0] can throw this PHP 8 warning.

The safer pattern would be one of:

$login = reset( $super_admins );

or:

$super_admins = array_values( $super_admins );
$login = $super_admins[0] ?? null;
Before patching locally, I would check whether anything is filtering or modifying the super admin list. Search custom plugins/theme code for site_admins or get_super_admins.

For production, I would not suppress warnings as the fix. Confirm the array shape first, then let Site Kit patch the access pattern.

This is good evidence and confirms the exact failure mode.

The important part is:

• get_super_admins() returns a non-empty array
• the only key is 5
• key 0 does not exist
• raw site_admins is {"5":"svenms"}

So the current check:

! empty( $super_admins )
is not sufficient before reading:

$super_admins[0]
The issue is not whether the site has a super admin. It does. The issue is that get_super_admins() does not guarantee a zero-based array.

For reproduction, a multisite install with a sparse site_admins option should be enough:

update_site_option( ‘site_admins’, array( 5 => ‘svenms’ ) );
Then any code path that assumes $super_admins[0] can trigger the PHP 8 warning.

The plugin-side fix should avoid assuming key 0, for example:

$login = reset( $super_admins );
or normalize first:

$super_admins = array_values( $super_admins );
$login = $super_admins[0] ?? null;
A site-side workaround would be to normalize the stored site_admins option, but that should not be necessary for Site Kit to avoid the warning.