Edit C:\Windows\System32\ServerManagerInternal\RDManagement\Send-RDMessage.xaml

<Activity mc:Ignorable="sads sap" x:Class="RDManagement.Send_RDMessage" this:Send_RDMessage.Title="[String.Format(&quot;Message from: {0}, Sent: {1}&quot;, Environment.UserName, DateTime.Now.ToString())]"
 xmlns="http://schemas.microsoft.com/netfx/2009/xaml/activities"
 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 xmlns:mpa="clr-namespace:Microsoft.PowerShell.Activities;assembly=Microsoft.PowerShell.Activities"
 xmlns:mpua="clr-namespace:Microsoft.PowerShell.Utility.Activities;assembly=Microsoft.PowerShell.Utility.Activities"
 xmlns:mv="clr-namespace:Microsoft.VisualBasic;assembly=System"
 xmlns:mva="clr-namespace:Microsoft.VisualBasic.Activities;assembly=System.Activities"
 xmlns:s="clr-namespace:System;assembly=mscorlib"
 xmlns:s1="clr-namespace:System;assembly=System"
 xmlns:s2="clr-namespace:System;assembly=System.Xml"
 xmlns:s3="clr-namespace:System;assembly=System.Core"
 xmlns:s4="clr-namespace:System;assembly=System.ServiceModel"
 xmlns:s5="clr-namespace:System;assembly=System.ComponentModel.Composition"
 xmlns:sa="clr-namespace:System.Activities;assembly=System.Activities"
 xmlns:sad="clr-namespace:System.Activities.Debugger;assembly=System.Activities"
 xmlns:sads="http://schemas.microsoft.com/netfx/2010/xaml/activities/debugger"
 xmlns:sap="http://schemas.microsoft.com/netfx/2009/xaml/activities/presentation"
 xmlns:scg="clr-namespace:System.Collections.Generic;assembly=System"
 xmlns:scg1="clr-namespace:System.Collections.Generic;assembly=System.ServiceModel"
 xmlns:scg2="clr-namespace:System.Collections.Generic;assembly=System.Core"
 xmlns:scg3="clr-namespace:System.Collections.Generic;assembly=mscorlib"
 xmlns:sd="clr-namespace:System.Data;assembly=System.Data"
 xmlns:sl="clr-namespace:System.Linq;assembly=System.Core"
 xmlns:sma="clr-namespace:System.Management.Automation;assembly=System.Management.Automation"
 xmlns:st="clr-namespace:System.Text;assembly=mscorlib"
 xmlns:this="clr-namespace:RDManagement"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <x:Members>
    <x:Property Name="RDManagementServer" Type="InArgument(x:String)">
      <x:Property.Attributes>
        <RequiredArgumentAttribute />
      </x:Property.Attributes>
    </x:Property>
    <x:Property Name="HostServer" Type="InArgument(x:String)">
      <x:Property.Attributes>
        <RequiredArgumentAttribute />
      </x:Property.Attributes>
    </x:Property>
    <x:Property Name="SessionId" Type="InArgument(x:Int32)">
      <x:Property.Attributes>
        <RequiredArgumentAttribute />
      </x:Property.Attributes>
    </x:Property>
    <x:Property Name="Title" Type="InArgument(x:String)" />
    <x:Property Name="Message" Type="InArgument(x:String)">
      <x:Property.Attributes>
        <RequiredArgumentAttribute />
      </x:Property.Attributes>
    </x:Property>
  </x:Members>
  <sap:VirtualizedContainerService.HintSize>570,613</sap:VirtualizedContainerService.HintSize>
  <mva:VisualBasic.Settings>Assembly references and imported namespaces for internal implementation</mva:VisualBasic.Settings>
  <sap:WorkflowViewStateService.ViewState>
    <scg3:Dictionary x:TypeArguments="x:String, x:Object">
      <x:Boolean x:Key="ShouldCollapseAll">True</x:Boolean>
    </scg3:Dictionary>
  </sap:WorkflowViewStateService.ViewState>
  <Sequence DisplayName="Send message to a remote session" sap:VirtualizedContainerService.HintSize="530,573">
    <Sequence.Variables>
      <Variable x:TypeArguments="sma:PSDataCollection(sma:ErrorRecord)" Name="Errors" />
    </Sequence.Variables>
    <sap:WorkflowViewStateService.ViewState>
      <scg3:Dictionary x:TypeArguments="x:String, x:Object">
        <x:Boolean x:Key="IsExpanded">True</x:Boolean>
      </scg3:Dictionary>
    </sap:WorkflowViewStateService.ViewState>
    <mpua:WriteVerbose DisplayName="Verbose: Input" sap:VirtualizedContainerService.HintSize="508,22" Message="[&quot;Management Server: &quot; + RDManagementServer + Environment.NewLine +&#xA;&quot;Host Server: &quot; + HostServer + Environment.NewLine +&#xA;&quot;Session ID: &quot; + SessionId.ToString() + Environment.NewLine +&#xA;&quot;Title: &quot; + Title + Environment.NewLine +&#xA;&quot;Message: &quot; + Message]" />
    <mpa:InlineScript Command="import-module $env:windir\System32\ServerManagerInternal\rdmanagement;&#xD;&#xA;Send-RemoteDesktopMessage -HostServer $using:HostServer -SessionId $using:SessionId -Title $using:Title -Message $using:Message -ManagementServer $using:RDManagementServer" sap:VirtualizedContainerService.HintSize="508,139" PSError="[Errors]">
      <sap:WorkflowViewStateService.ViewState>
        <scg3:Dictionary x:TypeArguments="x:String, x:Object">
          <x:Boolean x:Key="IsPinned">True</x:Boolean>
        </scg3:Dictionary>
      </sap:WorkflowViewStateService.ViewState>
    </mpa:InlineScript>
    <If Condition="[Errors.Count &gt; 0]" sap:VirtualizedContainerService.HintSize="464,208">
      <sap:WorkflowViewStateService.ViewState>
        <scg3:Dictionary x:TypeArguments="x:String, x:Object">
          <x:Boolean x:Key="IsPinned">True</x:Boolean>
        </scg3:Dictionary>
      </sap:WorkflowViewStateService.ViewState>
      <If.Then>
        <TerminateWorkflow Exception="[Errors(0).Exception]" sap:VirtualizedContainerService.HintSize="200,22" />
      </If.Then>
    </If>
  </Sequence>
</Activity>

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