.csproj bug in Asp .NET Core MVC - asp.net-core

Question

I have wanted to create new table in my database (SQLite), so I created new Model and used it in ApplicationDbContext class like this:
public DbSet<AppUser> AppUsers { get; set; }
public DbSet<Report> Reports { get; set; }
Then executed the command later:
dotnet ef migrations add Report
I can see migration file.
In Startup.cs file I have:
services.AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(connectionString));
services.AddDbContext<AppIdentityDbContext>(options => options.UseSqlServer(connectionString));
In EFRepository.cs:
public IQueryable<AppUser> AppUsers
=> ctx.AppUsers;
public IQueryable<Report> Reports => ctx.Reports;
After this somehow suddenly I received many errors connected with this file ( .csproj):
<Project Sdk="Microsoft.NET.Sdk.Web">
<PropertyGroup>
<TargetFramework>netcoreapp3.0</TargetFramework>
<AssemblyName>Mushrooms</AssemblyName>
<RootNamespace>Mushrooms</RootNamespace>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="3.0.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore" Version="3.0.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="3.0.0">
<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
<PrivateAssets>all</PrivateAssets>
</PackageReference>
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="3.0.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.0.0">
<PrivateAssets>all</PrivateAssets>
<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
</PackageReference>
<PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="3.0.0" />
<PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="3.0.0" />
<PackageReference Include="Newtonsoft.Json" Version="12.0.2" />
</ItemGroup>
</Project>
I checked dotnet --info command, but I can't see incompatibility.
Three of the errors:
Invalid markup declaration '<'
Invalid markup declaration '
Invalid token "" at root level of document.
and many more in every line of this file.
This errors have occured when system was starting up.
I am using Asp .NET Core MVC 3.0.0.
Before this everything was working fine, any suggestions?

Answer 1

I try to create blank .net core 3.0 project and this csproj file is working fine
<Project Sdk="Microsoft.NET.Sdk.Web">
<PropertyGroup>
<TargetFramework>netcoreapp3.0</TargetFramework>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="3.1.0" />
</ItemGroup>
</Project>
Try to check your project extension file should be .csproj