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It appears that older versions of visual studio (currently i use vs2019) leave attributes in the csproj file

that cause this behavior. I had to manually clean all csproj files.

Buckup your files before making any changes manually.

Just to give an example, i include the contents of a csproj file before and after the changes.

Before

<?xml version="1.0" encoding="utf-8"?>
<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net48</TargetFramework>
    <EnableDefaultItems>False</EnableDefaultItems>
    <GenerateAssemblyInfo>False</GenerateAssemblyInfo>
  </PropertyGroup>
  <PropertyGroup>
    <LangVersion>7.2</LangVersion>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
    <AppDesignerFolder>Properties</AppDesignerFolder>
    <RootNamespace>cAlgo</RootNamespace>
    <AssemblyName>Lib Alg</AssemblyName>
    <FileAlignment>512</FileAlignment>
    <CheckForOverflowUnderflow>True</CheckForOverflowUnderflow>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="cTrader.Automate" Version="1.*" />
  </ItemGroup>
  <ItemGroup>
    <Reference Include="alglibnet2">
      <HintPath>..\..\..\..\..\Visual Studio Projects\- Install\AlgLib\alglibnet2.dll</HintPath>
    </Reference>
  </ItemGroup>
  <ItemGroup>
    <Compile Include="Lib Alg.cs" />
    <Compile Include="Properties\AssemblyInfo.cs" />
  </ItemGroup>
  <ItemGroup>
    <ProjectReference Include="..\..\Lib\Lib\Lib.csproj">
      <Project>{736B9155-17FD-4663-8D68-60CD78F36172}</Project>
      <Name>Lib</Name>
    </ProjectReference>
  </ItemGroup>
</Project>

After

<?xml version="1.0" encoding="utf-8"?>
<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net48</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="cTrader.Automate" Version="1.*" />
  </ItemGroup>
  <ItemGroup>
    <Reference Include="alglibnet2">
      <HintPath>..\..\..\..\..\Visual Studio Projects\- Install\AlgLib\alglibnet2.dll</HintPath>
    </Reference>
  </ItemGroup>
  <ItemGroup>
    <ProjectReference Include="..\..\Lib Alg\Lib Alg\Lib Alg.csproj" />
  </ItemGroup>
  <ItemGroup>
    <ProjectReference Include="..\..\Lib\Lib\Lib.csproj" />
  </ItemGroup>
</Project>