The 5.1 release introduced significant enhancements over previous versions, focusing on security, usability, and community feedback:
If you are still on WMF 5.0, upgrading to 5.1 brings tangible improvements: wmf 5.1
"WMF 5.1 requires .NET Framework 4.5 or higher" Fix: Download and install .NET 4.5.2 or .NET 4.8 from Microsoft before retrying. focusing on security