问题
I have setup the basic application in Blazor in Microsoft Visual Studio Community 2019 Version 16.1.3 and I have tried both of the versions of .NET Core SDK 3.0.100-preview5-011568 and SDK 3.0.100-preview6-012264.
Also I have installed the Blazor extension but when I am building without any modification in any files, the build fails with the following error:
"The type or namespace "App" could not be found.
Any help will be highly appreciated. Thanks.
回答1:
To use Blazor you need to have VS2019 preview edition or enable preview features on VS2019 by checking
Tools -> Options -> Environment -> Preview Features -> Use previews of the .NET Core SDK
or on the older versions of VS2019
Tools -> Options -> Projects and Solutions -> .NET Core -> Use previews of the .NET Core SDK
checkbox, then reload the solution and build.
回答2:
Addition to @SᴇM answer, please make sure you are using latest version of Visual studio. For my case, I followed the same steps mentioned by @SᴇM but still option Blazor App option not shown.
After that, I updated visual studio to 16.3.7 and now option is visible while creating new project. :)
来源：https://stackoverflow.com/questions/56576553/blazor-the-type-or-namespace-name-app-could-not-be-found-are-you-missing-a-us