Bulk Edit VRA – Update Default Gateway

I’m working on a script that will edit the default gateway of VRAs.  I’m getting the following error while running the script:

PS C:\Windows\system32> TerminatingError(Invoke-RestMethod): "Request Error
The server encountered an error processing the request. Please see the service help page for constructing valid requests to the service."


Exception             : System.Net.WebException: The remote server returned an error: (400) Bad Request.
                           at Microsoft.PowerShell.Commands.WebRequestPSCmdlet.GetResponse(WebRequest request)
                           at Microsoft.PowerShell.Commands.WebRequestPSCmdlet.ProcessRecord()
TargetObject          : System.Net.HttpWebRequest
CategoryInfo          : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-RestMethod], WebException
FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand
ErrorDetails          : Request Error
                        The server encountered an error processing the request. Please see the service help page for constructing valid requests to the service.
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at <ScriptBlock>, <No file>: line 102
PipelineIterationInfo : {}
PSMessageDetails      :

The following is found in the logfile.csv

Exception NullReferenceException (Object reference not set to an instance of an object.), cannot be serialized to preserve Stack, skipping. System.NullReferenceException: Object reference not set to an instance of an object.

   at Zerto.Zvm.Services.Vra.VraInfo.DynamicVraAddressTracker.SetVraBandwidthGroup(HostIdentifier host, String bwGroup) in E:\blv_u2\dev\system\Zvm\Services\Vra\Zerto.Zvm.Services.Vra.VraInfo\DynamicVraAddressTracker.cs:line 301

   at Zerto.Zvm.Vra.Management.VraManagement.HostTracker.ChangeVraBandwidthGroup(HostIdentifier host, String bwGroup) in E:\blv_u2\dev\system\Zvm\Vra\Zerto.Zvm.Vra.Management\VraManagement\HostTracker.cs:line 983

And finally, here is my script (excluding the connection and session creation info, which I know is working because sessions are connecting correctly and variables are being populated with correct data.

#Get VRAs
$GetVRAsURL = $BaseURL + "vras"
$vraList = Invoke-RestMethod -Uri $GetVRAsURL -TimeoutSec 100 -Headers $zertoSessionHeader -ContentType $TypeJSON

#Parse $vraList
foreach($vra in $vraList){

    $vraIdentifier = $vra.VraIdentifier
    $vraName = $vra.VraName
    $defaultGW = $vra.VraNetworkDataApi.DefaultGateway
    $vraIP = $vra.VraNetworkDataApi.VraIPAddress
    

    #Build VRA Edit URL
    $editVRAsURL = $baseURL + "vras/" + $vraIdentifier 

    if($defaultGW -eq $newVRADefaultGateway){
        #Skip update if GW is already correct
        Write-host "Skipping $vraName"
        Write-host "Current GW = $defaultGW"
        Write-host "Default gateway already $defaultGW"
    }else {
        #Change GW to $newVRADefaultGateway
        Write-host "Changing $vraName default gateway from $defaultGW to $newVRADefaultGateway"

        #Building JSON body to send to API
        $JSON = 
            "{
            ""VraNetworkDataApi"": {
                ""DefaultGateway"": ""$newVRADefaultGateway"",
                ""SubnetMask"": ""255.255.255.224"",
                ""VraIPAddress"": ""$vraIP"",
                ""VraIPConfigurationTypeApi"": ""Static""
                }
            }"
        
        
        Write-host "Executing $JSON"

        #try/catch API command
        try {
            Invoke-RestMethod -Method PUT -Uri $editVRAsURL -Body $JSON -Headers $zertoSessionHeader -ContentType $TypeJSON -TimeoutSec 60
        }
        catch {
            Write-Host $_.Exception.ToString()
            $error[0] | Format-List -Force   
        }#end try/catch

        Write-host "Waiting 30 seconds before starting next VRA Edit"
        sleep 30 
    }#end if/else
}#end foreach

# Stopping logging
Stop-Transcript

Anyone have any ideas what could possibly be causing the Null exception in the PUT statement?