If you attempt to launch SeqMan NGen, without an updated .NET Framework Service Pack 1 (Windows) or Mono package (Mac) installed, you may receive an error message, and SeqMan NGen may fail to open.
The best way to ensure the correct software is installed is to perform all recommended updates when prompted by your operating system.
To instead resolve this issue manually:
•Windows – Download and install .NET Framework 4.7.2 from https://www.microsoft.com/net/download/windows/run.
•Macintosh – Download and install the Mono 5.10.1 stable package from http://www.mono-project.com/download/stable/#download-mac.