Bulk Change AD User Login Name with powershell

# Active Directory Module Install
#Import-Module ActiveDirectory

# CSV file:
$kullanicilar = Import-Csv -Path "C:\news.csv"

# Domain name:
$domain = "guler.com"

# Logon Name Update:
foreach ($kullanici in $kullanicilar) {
    $oldUsername = $kullanici.old_username
    $newLogonName = $kullanici.new_username

    if ($oldUsername -and $newLogonName) {
        try {
            # User find and update:
            $user = Get-ADUser -Identity $oldUsername -ErrorAction Stop
            $newUserPrincipalName = "$newLogonName@$domain"
            Set-ADUser -Identity $user -UserPrincipalName $newUserPrincipalName -SamAccountName $newLogonName -ErrorAction Stop
            Write-Host "$oldUsername için $newUserPrincipalName olarak güncellendi."
        } catch {
            Write-Host "$oldUsername için hata oluştu: $_"
        }
    } else {
        Write-Host "Hata: Boş veya geçersiz kullanıcı adı tespit edildi. old: '$oldUsername', new: '$newLogonName'"
    }
}

When you change a user's samAccountName in Active Directory, the user's SID (Security Identifier) ​​and GUID (Globally Unique Identifier) ​​do not change.

At the end of this process the following Attributes will be changed:

• msDS-Principalname
• sAMAccountName
• userPrincipalName
• mailNickname(*If there is an Exchange)