Web player service failing to start after updating to Lead discovery 3.0 or later.

When upgrading Lead discovery to 3.0 or higher from an earlier version you can see the following error (or similar) in the logs after updating the services:

Spotfire.Dxp.Worker.Host.WorkerHost;"Failed to start worker.
System.IO.FileNotFoundException: Could not load file or assembly 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' or one of its dependencies. The system cannot find the file specified.
File name: 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'
at System.ModuleHandle.ResolveMethod(RuntimeModule module, Int32 methodToken, IntPtr* typeInstArgs, Int32 typeInstCount, IntPtr* methodInstArgs, Int32 methodInstCount)

This is due to changed system requirements for Lead discovery 3.0 compared to earlier versions, where you need to have a higher version of the .Net framework installed.

To resolve the issue update to the latest .Net version on the Node manager machine.

For further information about .Net installation, please see this link:

https://docs.microsoft.com/en-us/dotnet/framework/install/

To check what version(s) of .Net you have installed run the following code in Powershell:

 Get-ChildItem 'HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP' -Recurse | Get-ItemProperty -Name version -EA 0 | Where { $_.PSChildName -Match '^(?!S)\p{L}'} | Select PSChildName, version

This will give you something similar to this indicating the .Net versions that are installed: