Everywhere the problem to this solution was mentioned as re-registering aspNet by using aspnet_regiis.exe. But this did not work for me.
Though this is a valid solution (as explained beautifully here)
but it did not work with Windows 8.
For Windows 8 you need to Windows features and enable everything under ".Net Framework 3.5" and ".Net Framework 4.5 Advanced Services".

These are the customer-reported issues addressed in 15.9.4:

• Visual Studio 15.9 duplicate loads open files on solution reload.
• All users can now connect to on-premise TFS servers through Team Explorer.
• Visual Studio 15.8.3 no longer expands metadata in ItemDefinitionGroup for project-defined items during GUI builds (worked in Visual Studio 15.8.2).
• Visual Studio has multiple tabs for the same file.
• System.ArgumentException: The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG)).
• LNK4099 PDB not found.
• Asset Catalog empty.
• /analyze fails for C++ code using /ZW.
• C++ compiler code optimization bug.
• Xamarin.iOS can't select image asset for Image View.
• iOS projects referencing a shared project containing image assets in an asset catalog fail to load on windows.
• Image not populating on iOS splashscreen in VS 15.8.6.
• Possible bad codegen on union/bitfield assignment in VS2017 15.8.
• Fix C# UWP Store 1201 Submission Issue.
• Fix C# UWP package creation error APPX1101: Payload contains two or more files with the same destination path 'System.Runtime.CompilerServices.Unsafe.dll'.
• Error MT2002: Failed to resolve 'System.Runtime.CompilerServices.AsyncValueTaskMethodBuilder' reference from 'System.Threading.Tasks.Extensions...'" when building a Xamarin.iOS project.
• Redirecting to a relative url doesn't work when using AndroidClientHandler.
• Debug information for typedefs of unnamed enums compiled with the C compiler is now restored.
• The spectre-mitigated x86 version of delayimp.lib is now built with /Qspectre mitigations enabled.
• Changes were made to how Asset Catalogs in Xamarin.iOS projects are loaded in order to reduce solution load time.
• We have updated Xamarin.Forms templates to use the latest version.
• We have fixed an issue with ASP.NET Core Web Applications being debugged through Kestrel that would show the error message "Unable to configure HTTPS endpoint. No server certificate was specified...".
• Enabling the AppInsights site extension in App Service from Visual Studio now happens through the use of specific Application Settings.

Security Advisory Notices

• An elevation of privilege vulnerability exists when the Diagnostics Hub Standard Collector Service improperly handles certain file operations. 

• XAML designer for UWP - control properties not displayed
• UWP XAML designer doesn't update elements on updating XAML code
• XAML properties and document structure
• Properties window not showing the properties when clicking an object
• Unable to see properties of any items
• Installation error when trying to connect to the Mac: "The Xamarin.iOS version installed on 'x' (12.8.0.2) is newer than your version".
• Fixed right click solution name in titlebar VS crash bug.
• Improved performance for customers with the Azure workload installed.
• Corrected errors during restore and build on SDK-based projects that use 3rd party SDKs to target UWP platforms.
• Fixed a bug in C# compiler where it was not properly warning customers about incomplete interface implementations.
• Improved error messaging in Visual Studio Tools for Kubernetes.
• Fixed error when adding a comment in PR for SymbolCheck. 

We’re shipping our latest patch release today to fix a handful of bugs in Bootstrap 4. While our focus remains on v5’s second alpha release (coming in the next couple weeks), we want to keep v4 as stable and reliable as possible. 

The leak was discovered on the company's AI GitHub repository and is said to have been inadvertently made public when publishing a bucket of open-source training data, Wiz said. It also included a disk backup of two former employees' workstations containing secrets, keys, passwords, and over 30,000 internal Teams messages. 

You'll have to migrate to .NET 5 in the near future, and this article will help you prepare for this inevitable migration and avoid the last-minute, unexpected problems that will come up if you procrastinate. 

How do callbacks, promises and async/await compare to each other? This article shows the same scenario using each of these three techniques so you can see the differences and choose which appeals most to you. 

Luckily a fix was already available. I updated to the latest Automapper version (12.0.1 at the moment of writing) and the issue disappeared.