Ошибка компилятора cs5001

I got this error when using the command Build Docker Image in Visual Studio 2022.

error CS5001: Program does not contain a static 'Main' method suitable for an entry point

The project built perfectly well in Windows but I tried to build a Linuxcontainer. Switching to Output Type Class Library solved the error but Docker Compose gave me this error instead:

CTC1031 Linux containers are not supported for

https://stackoverflow.com/a/74044317/3850405

I tried explicitly using a Main method like this but it did not work:

namespace WebApplication
{
    public class Program
    {
        public static void Main(string[] args)
        {

I have no idea why but this solved it for me:

Gives error:

FROM mcr.microsoft.com/dotnet/aspnet:6.0 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/sdk:6.0 AS build
WORKDIR /src
COPY ["src/Services/Classification/ClassificationService.Api/ClassificationService.Api.csproj", "Services/Classification/ClassificationService.Api/"]

RUN dotnet restore "Services/Classification/ClassificationService.Api/ClassificationService.Api.csproj"
COPY . .
WORKDIR "/src/Services/Classification/ClassificationService.Api"
RUN dotnet build "ClassificationService.Api.csproj" -c Release -o /app/build

Works:

FROM mcr.microsoft.com/dotnet/aspnet:6.0 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/sdk:6.0 AS build
WORKDIR /src
COPY ["src/Services/Classification/ClassificationService.Api/ClassificationService.Api.csproj", "src/Services/Classification/ClassificationService.Api/"]

RUN dotnet restore "src/Services/Classification/ClassificationService.Api/ClassificationService.Api.csproj"
COPY . .
WORKDIR "/src/src/Services/Classification/ClassificationService.Api"
RUN dotnet build "ClassificationService.Api.csproj" -c Release -o /app/build

Notice the double /src in the working example.

I read that you had to place the Dockerfile at the same level as .sln file but in my case the files are separated by four levels.

https://stackoverflow.com/a/63257667/3850405

As OP did not restricted to WinForms, and I have this error because of a mixed WinForms => WPF approach, I feel that is OK to answer here.

In my case I have .NET Framework 4.8 that gets data from an ancient Outlook .pst file; on top of this I want to display contacts with a WPF UI — I know, I know, why not with a WinForms?

For WPF, I had to add System.Xaml, PresentationCore and PresentationFramework and of course deleted the Form1.cs and Program.cs causing the error msg «CS5001 Program does not contain a static ‘Main’ method suitable for an entry point» that immediately appeared.

After some SO Googling, I came here and to another thread and came up with this change at .csproj:

  <ItemGroup>
    <!--<Page Include="App.xaml">
      <Generator>MSBuild:Compile</Generator>
      <SubType>Designer</SubType>
    </Page>-->
    <!-- ^^^^^^^^ ERROR ^^^^^^^^ -->
    <!-- Above leads to an error Message "CS5001 Program does not contain a static 'Main' method suitable for an entry point"-->
    
    <!-- Below is the fix for WPF in NET Framework --> 
    <ApplicationDefinition Include="App.xaml">
      <Generator>MSBuild:Compile</Generator>
      <SubType>Designer</SubType>
    </ApplicationDefinition>
    ...
  <ItemGroup>

PS: As a side note, when you unload the project and click Edit Project File and ask for Find App.Xaml with CTRL-F do you notice that — sometimes, at least — the default scope is Current Project? And as your Project is unloaded, although you are in the .csproj it does not find anything inside the current .csproj?

I lose a lot of minutes in that before I realize that I had to change scope to Current Document…