introduction

in.net core3.0, the using declaration is not available in C# 7.3 after it is used in the code. Please use language version 8.0 or higher.” The solution is

error message

CS8370

0

1

2 Feature ‘using declarations is not available in C# 7.3.please use language version 8.0 or greater.

3

4

Severity	Code	Description	Project	File	Line	Suppression State
6 Error	5 6 CNPCApi 7	D:\Project\NetCore\CNPCApi\CNPCApi\Program.cs	14	Active

solution

Add the following property node

to the solution file.csproj (right-click in explorer and edit via vs open) file

<PropertyGroup>
   <LangVersion>preview</LangVersion>
</PropertyGroup>
或
<PropertyGroup>
   <LangVersion>8.0</LangVersion>
</PropertyGroup>

add after save, recompile successfully, oh