If you wanted to build a Windows Store App for Windows 8.1, you had to use .NET 4.5.1. You couldn't target 4.5. This "forced upgrade" strategy was Microsoft trying to push the ecosystem forward, but it created headaches for IT departments that were still on Windows 7. While 4.5.1 was deployable on Windows 7, the tight coupling with the controversial Windows 8.1 platform caused some friction in enterprise adoption circles.
At its launch, .NET 4.5.1 was bundled with and Windows Server 2012 R2 . It was also made available for download on Windows 7 SP1, Windows Vista SP2, and Windows Server 2008/2012. Lifecycle Status microsoft dotnet framework 4.5.1
Modernize applications by retargeting them to .NET Framework 4.8.1 or migrating to the cross-platform .NET 8.0/9.0 ecosystem. If you wanted to build a Windows Store App for Windows 8
Here’s an interesting, balanced review of — keeping in mind it was released in October 2013 , so “interesting” here means historically significant and pragmatic for its time . While 4
If you are still running on 4.5.1, you are running on an unsupported framework (End of Life: January 2016). Migration to at least 4.6.2 (or ideally .NET 6/8) is critical for security. However, for a nostalgic look back, 4.5.1 was when Microsoft really hit its stride in balancing power with developer productivity.