Troubleshooting steps

$connectionName = "M365"

if ($PSVersionTable.PSEdition -ne "Desktop") {
    Write-Error "This script must be run in a Windows PowerShell 5.x window (not a PowerShell 7.x window). Please open a Windows PowerShell window and re-run." -ErrorAction Stop
}

$beaconInstallPath = Get-ItemPropertyValue -Path "HKLM:\SOFTWARE\WOW6432Node\ManageSoft Corp\ManageSoft" -Name ETDPInstallDir

if (!$beaconInstallPath) {
    Write-Error "Could not find beacon installation path. Are you running this on a beacon?" -ErrorAction Stop
}

Add-Type -Path "$beaconInstallPath\DotNet\bin\Flexera.Beacon.Common.dll"

$connection = ([Flexera.Beacon.Common.BeaconDataLayerFactory]::Create()).LoadConfigurations().GetConnectionsByName($connectionName)

if (!$connection) {
    Write-Error "No connection with name '$connectionName' found" -ErrorAction Stop
}

# Build hash table of parameters for lookup
$params = @{}; $connection.RemoteConnectionParameters | %{ $params[$_.Name] = $_.Value }

$params = @{}

$params.proxyServer = Read-Host "Enter web proxy URL (example: http://my-proxy:8080), or leave blank if no proxy is needed"

if ($params.proxyServer) {
    $params.proxyUsername = Read-Host "Enter username for web proxy authentication, or leave blank if no authentication is required"

    if ($params.proxyUsername) {
        $params.proxyPassword = (Get-Credential $params.proxyUsername -Message "Enter password for web proxy authentication").GetNetworkCredential().Password
    }
}

$params.TokenEndpoint = Read-Host "Enter Token Endpoint (example: https://login.microsoftonline.com/common/oauth2/v2.0/token)"

$params.ClientID = Read-Host "Enter Application (client) ID (example: 5bb1a5a2-0d97-4335-9448-119f7b27aff9)"

$useAuthCode = (Read-Host "Use Authorization Code authentication flow? (Y or N)").ToUpper()

if ($useAuthCode[0] -eq "Y") {
    $params.AuthType = "Authorization Code"

    $params.RedirectUrl = Read-Host "Enter Redirect URL (example: https://login.microsoftonline.com/common/oauth2/nativeclient)"

    $params.AuthorizationEndpoint = Read-Host "Enter Authorization Endpoint (example: https://login.microsoftonline.com/common/oauth2/v2.0/authorize)"

    $params.RefreshToken = Read-Host "Enter Refresh Token"
} else {
    $params.AuthType = "Client Credentials"

    $params.ClientSecret = Read-Host "Enter Client Secret"
}

if ($params.proxyServer) {
    [System.Net.WebRequest]::DefaultWebProxy = New-Object System.Net.WebProxy($params.proxyServer)

    if ($params.proxyUsername) {
        $credCache = New-Object System.Net.CredentialCache

        $cred = New-Object System.Net.NetworkCredential($params.proxyUsername, $params.proxyPassword)

        $credCache.Add($params.proxyServer, "Basic", $cred)

        [System.Net.WebRequest]::DefaultWebProxy.Credentials = $credCache
    }
}

Write-Output "Connecting to Microsoft 365 API using the following parameters:"

$params

if ($params.AuthType -eq "Authorization Code") {
    $tokenArgs = @{
        client_id = $params.ClientID
        redirect_uri = $params.RedirectUrl
        refresh_token = $params.RefreshToken
        grant_type = "refresh_token"
    }
} else {
    $tokenArgs = @{
        client_id = $params.ClientID
        scope = "https://graph.microsoft.com/.default"
        client_secret = $params.ClientSecret
        grant_type = "client_credentials"
    }
}

[System.Net.ServicePointManager]::SecurityProtocol = [System.Net.SecurityProtocolType]::Tls12

$response = Invoke-RestMethod -Uri $params.TokenEndpoint -Method POST -ContentType "application/x-www-form-urlencoded" -Body $tokenArgs

if (-not $response.access_token) {
    Write-Error "No access token returned" -ErrorAction Stop
}

Write-Host "Access token successfully obtained"

$headers = @{
    Authorization = "Bearer $($response.access_token)"
    ContentType = "application/json"
    ConsistencyLevel = "eventual"
}

$result = Invoke-RestMethod -Method GET -Uri 'https://graph.microsoft.com/v1.0/Users?$select=id,givenName,surname,userPrincipalName,assignedLicenses&$top=2&$count=true' -Headers $headers

Write-Output "Returned result with $($result."@odata.count") users"

Write-Output "First users in result set:"

$result.value

$result = Invoke-RestMethod -Method GET -Uri 'https://graph.microsoft.com/v1.0/subscribedSkus' -Headers $headers

Write-Output "Returned result with $($result.value.Count) subscribed SKUs"

Write-Output "Subscribed SKUs:"

$result.value