Visual Studio and the .NET Framework
The .NET SDK assemblies for Dynamics 365 for Customer Engagement are built on .NET Framework version 4.6.2.
You can use Visual Studio to build your managed code applications using .NET Framework version 4.6.2 or later.
Important
You should build any custom client applications using Microsoft .NET Framework 4.6.2 or later. Starting with the Dynamics 365 for Customer Engagement apps version 9.0, only applications using Transport Level Security (TLS) 1.2 or better security will be allowed to connect. TLS 1.2 is not the default protocol used by .NET Framework 4.5.2, but it is in .NET Framework 4.6.2.
Enforcement of this higher standard for security will only be applied to Dynamics 365 for Customer Engagement apps version 9.0 at this time. If your clients are designed to connect to any version or deployment type you can prepare by re-compling the application to use .NET Framework 4.6.2. More information: Blog Post: Updates coming to Dynamics 365 Customer Engagement (on-premises) connection security
The SDK APIs available in Microsoft.CrmSdk.XrmTooling.CoreAssembly and other "CrmSdk" NuGet packages do not support .NET Core code development.
Tip
When installing .NET Framework 4.6.2 on your development computer, be sure to install the developer pack and not just the run-time. This will enable the 4.6.2 framework to be chosen in the New Project dialog box of Visual Studio and in the target framework drop-down menu of the project’s properties.
You can use a Visual Studio Community edition for development.
More information: Support for .NET Framework versions
For a complete statement of supported and unsupported development, see Supported Extensions for Dynamics 365 Customer Engagement (on-premises).