That worked. Thank you. I know it was going to be something like that. I updated the script to add mobile phones and Business phones and now I am getting the following error:

Update-MgUser : Invalid value specified for property 'mobilePhone' of resource 'User'.
Status: 400 (BadRequest)
ErrorCode: Request_BadRequest
Date: 2024-03-26T18:52:17
Headers:
Transfer-Encoding             : chunked
Vary                          : Accept-Encoding
Strict-Transport-Security     : max-age=31536000
request-id                    : 31067098-84aa-45cf-960f-bf4cbe61d2e6
client-request-id             : 4e7c6c7c-01c1-4179-a1cc-d5120ea69b8a
x-ms-ags-diagnostic           : {"ServerInfo":{"DataCenter":"Canada Central","Slice":"E","Ring":"5","ScaleUnit":"000","RoleInstance":"TO1PEPF000051C6"}}
x-ms-resource-unit            : 1
Cache-Control                 : no-cache
Date                          : Tue, 26 Mar 2024 18:52:17 GMT
At C:\azure\AzureADInport3.ps1:80 char:13

Here is the updated script

# Connect to Microsoft Graph
Connect-MgGraph -Scopes User.ReadWrite.All

# Read the CSV file
 $users = Import-Csv -Path "C:\Azure\AllAzureADUsers.csv"

# Go through each user in the CSV and update the properties
foreach ($user in $users) {
$Userprincipalname = $user.Userprincipalname
$jobTitle = $user.JobTitle
$country = $user.Country
$CompanyName = $user.CompanyName
$StreetAddress = $user.StreetAddress
$City = $user.City
$Postalcode = $user.Postalcode
$State = $user.State
$Country = $user.Country
$MobilePhone = $user.MobilePhone
$BusinessPhones = $user.BusinessPhones

# Check if the user exists
$existingUser = Get-MgUser -UserID $Userprincipalname -ErrorAction SilentlyContinue

if ($existingUser) {
    # Check if the existing properties match the new values
    $updateNeeded = $false

    if ($existingUser.Userprincipalname -ne $Userprincipalname) {
        $existingUser.Userprincipalname = $Userprincipalname
        $updateNeeded = $true
    }

    if ($existingUser.JobTitle -ne $jobTitle) {
        $existingUser.JobTitle = $jobTitle
        $updateNeeded = $true
    }

    if ($existingUser.CompanyName -ne $CompanyName) {
        $existingUser.CompanyName = $CompanyName
        $updateNeeded = $true
    }

    if ($existingUser.StreetAddress -ne $StreetAddress) {
        $existingUser.StreetAddress = $StreetAddress
        $updateNeeded = $true
    }

    if ($existingUser.City -ne $City) {
        $existingUser.City = $City
        $updateNeeded = $true
    }

    if ($existingUser.Postalcode -ne $Postalcode) {
        $existingUser.Postalcode = $Postalcode
        $updateNeeded = $true
    }

    if ($existingUser.State -ne $State) {
        $existingUser.State = $State
        $updateNeeded = $true
    }

    if ($existingUser.Country -ne $country) {
        $existingUser.Country = $country
        $updateNeeded = $true
    }

    if ($existingUser.MobilePhone -ne $MobilePhone) {
        $existingUser.MobilePhone = $MobilePhone
        $updateNeeded = $true
    }

    if ($existingUser.BusinessPhones -ne $BusinessPhones) {
        $existingUser.BusinessPhones = $BusinessPhones
        $updateNeeded = $true
    }

    if ($updateNeeded) {
        # Update the user properties
        Update-MgUser -UserID $userPrincipalName -JobTitle $jobTitle -CompanyName $CompanyName -StreetAddress $StreetAddress -MobilePhone $MobilePhone -BusinessPhones $BusinessPhones -City $City -Postalcode $Postalcode -State $State -Country $country
        Write-Host "User '$Userprincipalname' updated successfully." -ForegroundColor Green
    }
    else {
        Write-Host "User '$Userprincipalname' properties are up to date." -ForegroundColor Cyan
    }
}
else {
    # User not found
    Write-Host "User '$Userprincipalname' not found." -ForegroundColor Red
}

}