Updating windows server remotely via Powershell - powershell

Question

Hello I have been trying to make this script work for some time now, but I keep running into problems. The script is written with multiple servers in mind, although I am just testing it only on one test system for now.
Following I will post the script.
#List of Servers
$SQLServer = #('testserver.net')
$ApplicationServer = #('testserver.net')
$Servers = #($SQLServer, $ApplicationServer)
$ServiceName = #('tomcat9', 'MSSQLSERVER')
#Information Message
Write-Host "Starting update process for the following Servers:" $Servers "and Services:" $ServiceName
#Gets status of Servers
ForEach ($Index in $Servers)
{
Invoke-command {Get-Service tomcat9} -comp $Servers[$Index]
Invoke-command {Get-Service -Name 'MSSQLSERVER'} -comp $Servers[$Index]
}
#Information Message
Write-Host "Stopping the specified Services:" $ServiceName
#Stops services
#Sequentially stops TomCat and then DB Applications
ForEach ($Index in $Servers)
{
$ArrayService = Invoke-Command {Get-Service tomcat9} -comp $Servers[$Index]
if ($ArrayService.Status -ne "Stopped")
{
Invoke-Command {Stop-Service tomcat9} -comp $Servers[$Index]
}
$ArrayService = Invoke-Command {Get-Service -Name 'MSSQLSERVER'} -comp $Servers[$Index]
if ($ArrayService.Status -ne "Stopped")
{
Invoke-Command {Stop-Service -Name 'MSSQLSERVER'} -comp $Servers[$Index]
}
}
#Information Message
Write-Host "Will now start Windows Updates on servers and reboot"
#Will Update Windows, automatically reboot and out the log in the specified directory. This will be done to all listed Servers
ForEach ($Index in $Servers)
{
$Scriptblock = {
Invoke-WUJob -Comp $Servers[$Index] -RunNow -Confirm:$false -Verbose -Script {
Install-WindowsUpdate -MicrosoftUpdate -NotCategory "SilverLight" -NotTitle "Preview" -AcceptAll -AutoReboot | Out-File C:\PSWindowsUpdate.log
}
}
Invoke-Command -Comp $Servers[$Index] -ScriptBlock $Scriptblock
}
#Information Message
Write-Host "Starting up Services again"
#Starting SQL Server and checking if its running, if not running it will give more time before the Script continues
ForEach ($Index in $SQLServer)
{
$ArrayService = Invoke-Command {Get-Service -Name $ServiceName} -comp $SQLServer[$Index]
$FilteredService = $ArrayService | where {$_ -like 'MSQL'}
while ($FilteredService.Status -ne 'Running')
{
Invoke-Command {Start-Service $FilteredService} -comp $SQLServer[$Index]
Write-Host $FilteredService.Status
Write-Host "SQL Service starting on " $SQLServer[$Index]
function Check-Status
{
Start-Sleep -seconds 30
$FilteredService.Refresh()
if ($FilteredService.Status -eq 'Running')
{
Write-Host "SQL Service running"
#Invoke-Command {Start-Service $ArrayService | where {$_ -like 'tomcat9'}} -comp $ApplicationServer
}
else
{
Check-Status
}
}
}
}
#Starting TomCat Service again
ForEach ($Index in $ApplicationServer)
{
Write-Host "MUMService starting on " $ApplicationServer[$Index]
#Invoke-Command {Start-Service $ArrayService | where {$_ -like 'tomcat9'}} -comp $ApplicationServer[$Index]
$ServiceStatus = Invoke-Command {Get-Service tomcat9} -comp $ApplicationServer[$Index]
if ($ServiceStatus.Status -eq 'Running')
{
Invoke-Command {Start-Service $ArrayService | where {$_ -like 'tomcat9'}} -comp $ApplicationServer[$Index]
Write-Host "MUM Service running"
}
else
{
Invoke-Command {Start-Service $ArrayService | where {$_ -like 'tomcat9'}} -comp $ApplicationServer[$Index]
}
}
ForEach ($Index in $Servers)
{
invoke-command {Get-Service mum_software_tomcat9} -comp $Servers[$Index]
invoke-command {Get-Service -Name 'MSSQLSERVER'} -comp $Servers[$Index]
}
Either my logic is really wrong, or this doesnt work this way in powershell, but when I try to execute the script as is, there is an error for the parameter 'ComputerName'. It says that the argument is null or empty. Provide an argument that is not null or empty and then try the command again. Apparently it does not like $SQLServer[$Index].
The update functionality itself seems to work by itself though.
What is wrong with this?