Does your TargetFramework look like this?
<TargetFramework>netstandart20</TargetFramework>
If so, the solution is probably just to fix the typo and make it look like this (standard, not standart):
<TargetFramework>netstandard2.0</TargetFramework>
1
solved netstandard 2.0 is not compatible with netstandard 2.0 [closed]