i've already searched and seen almost all in the web and in the forum, but i can't deal with that.
What I'm trying to do is to obtain an installer and then an exe of my form application by using c# in visual studio 2019.
So, i've followed that tutorial:
https://www.youtube.com/watch?v=fehVTLNQorQ&ab_channel=FoxLearn
so i correctly obtain the setup file. Then, when i launch it, it installs and if i try to run it i get that error: "You're trying to open a file type system .dll"
What i'm doing wrong?
I also structured my main class as in that response:
Changing a source file to compile Main() method in a project, in VS c# console application
I also used that suggested setting (sorry for non english language but it's quite understandable):
Is there somebody that can help me? thanks a lot
Some things you may want to check:
If you have more than one project in your solution, make sure that the main project is marked as Start-up project. On the solution explorer, right- click on the main project and select "Set as start-up project".
If you only have one project in your solution, check that no .exe is being produced in the corresponding bin folder. If it is, go to your project properties, inside Debug, and make sure that the option "Start project" is selected. You can also try to select the option "Start external program" and browse to the .exe in your bin folder (although the result should be the same).
If no .exe is produced, you may want to have a look at this post. It is similar to you problem I think but the other way round. I looks that the UseAppHost should be True for your case
You have to choose "Publish Items" and not "Primary Output" when you add a "Project Output" in "Application Folder" for .Net Core 3.1 in the setup project created by Visual Studio Installer Projects Extension.
# Alessio Orlando.
Based on my test, there is a different step between adding different project to the installer.
For WPF App(.NET Framework) project and Windows Forms App(.NET Framework) project: You could choose Primary output when you add a "Project output" in "Application Folder" in the setup project.
For WPF Application(.NET Core) project and Windows Forms App: As gigiabbrescia said, you have to choose Publish Items when you add a "Project Output" in "Application Folder" in the setup project.
Finally, there will be an .exe file in your installation directory after installing your Setup (Like the picture below). And you could click on your .exe file to run the program.
Is it possible to use NUnit3 Beta in VS2015RC?
I've just created a new Library Project (Package) and added NUnit and created a simple test to show the errors I'm getting.
Does it have some dependency on an older version of the framework?
project.json
Test Class
Update
The Release Notes say:
To work around this issue, follow these steps: Right-click the project
in which the errors are reported in Solution Explorer, and then click
Unload Project. Right-click again on the project in Solution Explorer,
and then click Edit .
Note In this command, represents the actual project
name. In the entry at the top of the project file that
has no Condition attribute, add the following:
true
Save and close the file. Right-click the project name in Solution
Explorer, and then click Reload Project.
However I cannot get this to work, I just get more warnings and errors in my errors window.
It is very likely that you should use xUnit.net for now,
https://github.com/aspnet/Testing/issues/34
NUnit won't be ported unless someone steps in.
I have mvc3 project when I start debugging it show messbox like this
How can i put this project into another executable project?Any idea?
Looks like there are multiple projects in the solution and start up project needs setting.
The MVC projects which you created needs to be the start up project.
To set a single startup project (VS 2010 and 2012)
1.In Solution Explorer, select the desired startup project within your solution.
2.On the Project menu, choose Set as StartUp Project.
Source: http://msdn.microsoft.com/en-us/library/a1awth7y(v=vs.80).aspx
Hope it helps
just go to the properties of the project then in the output tab change the output type from class library into executable .
after did this run your project.
I agree with Daniel: Click right on your MVC3 project, and select "Set as StartUp Project".
I downloaded a C# project and I wish to debug the project to see how an algorithm implementation works.
The project has come in a Folder, inside this folder there are -
.sln file and
a folder which has source files and a .csproj file.
I installed Visual Studio and opened the .sln file present in the main folder. I built the project successfully, but when I try to debug the project I get this message:
A project with an Output type of Class Library cannot be started directly In order to debug this project, add an executable project to this solution which references the library project. Set the executable project as the startup project.
The strange part is that I don't see a main function anywhere.
What should I do to get round this hiccup?
The project you have downloaded compiles into a dll assembly and provide a set of classes with implemented functionality.
You should add to your solution a new project with Output Type of either Console Application or Windows Application (VS Add Project wizard will offer you different templates of Projects).
In the newly added project, you can implement logic to test your Class Library.
Output type of the project you can find and change by the following steps:
Right click on project in Solution Explorer -> Properties.
In opened tab with properties select Application and there will be ComboBox marked with Output Type label.
Just right click on the Project Solution
A window pops up.
Expand the common Properties.
Select Start Up Project
In there on right hand side Select radio button with Single Startup Project
Select your Project in there and apply.
That's it. Now save and build your project. Run the project to see the output.
This was the solution that worked for me since I couldn't find 'Common Properties' option.
Select your topmost level project in Solution Explorer.
Go to Project, and in contextual menu Set as StartUp Project.
See also: A project with an Output type of Class Library cannot be started directly
Just needs to go:
Solution Explorer-->Go to Properties --->change(Single Startup project) from.dll to .web
Then try to debug it.
Surely your problem will be solved.
The strange part is that I don't see a main function anywhere.
That is exactly your problem. The project merely creates a DLL. It has no executable to run.
You will need to add a second project, which is an executable which references the other project, and calls something in it.
1) Right Click on **Solution Explorer**
2) Go to the **Properties**
3) Expand **Common Properties**
4) Select **Start Up Project**
5) click the radio button (**Single Start_up Project**)
6) select your Project name
7) Then Debug Your project
Right Click on "Solution Explorer" -> "Properties"
Expand "Common Properties"
Select "Start Up Project"
click the radio button "Single Start_up Project"
select your Project name from the drop down list.
If still not working after the above steps, then try this.
Expand solutions explorer.
Right click on project name -> "Properties"
Go to "Application" tab
Select "Output type"
From the drop down list select the appropriate type according to your application.
"Windows application" or
"Console application"
Then save (ctrl + S)
Try debugging (F5)
You'll need some kind of app (Console Apps are my favorite for debugging, but a WinForm will do) which uses your Class Library. Just add a new project (in the same solution) of a Console Application or Windows Forms Application, and add a reference to your current project. Once you've done that, make any calls you need, set your break points, and go to town.
I had a similar issue when trying to use the Experimental Instance of Visual Studio 2013. This was for a vsix project (Creating Snippets).
Solution was:
Right Click Project in Solution Explorer > Properties > Debug
Setting the Start Action to "Start external program" and using the following path:
C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\devenv.exe
This option was set to "Start project" which won't work for the application output type Class Library, which caused that same error.
Note: Yours may differ depending on how you installed VS.
Error solutions is that you have already open your project but by mistake you have selected another class library .. that's reason this error is showing ... so what u need to do you u just select u r project then right click on u r project
after right click u can see the list box and select the "Set as start up project " option .
Accepted answer works if your solution has a project that compiles to an exe. If your solution does not have any projects that compile to an exe, then you have to use 'Start external program'.
VS2019 instructions:
right click -> properties on the main solution
debug, start external program, and add command line arguments
VS2022 instructions:
right click -> properties on the main solution
scroll down to Debug
Debug > General > Open debug launch profiles UI
left click the 'new' icon in the top left, select 'executable'
fill it out as per VS2019 (pick the exe and add command line arguments)
when clicking the start button, first select the profile you made
Suppose you have multiple project in the solution. Select the project that you want to view in browser and select 'Set as StartUp Project'. In your multiple project soln which was the main, the visual studio was unable to identify. this was the main problem.
You can right click the Class Library project and from the drop-down choose Initialize Interactive C# which will load your project context and you can work it in the interactive session.
In my case, the cause was that one of my projects in the solution wasn't loaded. The reason it couldn't load properly was that the file path length of one of the files was too long. Upon deleting this long file, I could reload the project, and build the solution.
If the question involves an Azure project, make sure you have the "Azure development" tool set installed, or when you go to run a solution you may get this same error.
Tools > Get Tools and Features... > Tick the box next to Azure development > Click install
None of the answers provided above helped me resolve this error, this is what resolved the issue for me.
Right click on the solution and select "Properties", which is in my case "Sintctech.Data".
Select the section called "Application".
Check what you have selected as your output type. If it is "Windows Application", change it to "Console Appication".
Rebuild and the problem should be fixed.
in my solution:
i have a class library project that compiles into a dll.
i have a web project.
(i have multiple solutions with different web projects but the same class library)
one of the files in the class project (utilities.cs) - all of a sudden won't compile into the .dll
i had made a change to this file, but the change wouldn't show on the website. so i put a breakpoint in the .cs file, and tried running it... breakpoint didn't get hit! eventually i put a breakpoint in the .aspx file that called the function. then i stepped the debugger one line on, so it would step into the .cs file, except i got the error:
"This source file has changed. It no longer matches the version of the file used to build the application being debugged."
so the code in utilities.cs is not being updated into the dll. which is weird, because code in my other .cs files IS being updated (i tried changing a few lines) and IS able to catch the debug.
any ideas how to fix this? or even what the cause of the problem is??
Try:
Right click on Solution in Solution Explorer -> Properties -> Configuration Properties -> Make sure Build checkbox is checked for your class library.
You need to find out why the DLL will not build:
Look at the output window for any errors
Check the Errors window
Fix the errors and try building again.
The dll that you are trying to debug is from an older version of your code that did compile OK and the debugger pickes that up and is trying to debug against that - it is complaining because the code and the dll no longer match.
Try doing a Build -> Clean on the solution and then rebuilding to see the errors.
When You adding new references to Web project You must choose "Projects" tab:
Projects lists all reusable components created from local projects.
Add or Remove References in Visual
Studio
Add a Reference to a Visual Studio
Project in a Web Site
Always rebuild all projects in Release and Debug mode.
I did exactly what #nightcoder said but a simple change was required. Go to Configuration Properties(Right click on Solution in Solution Explorer -> Properties -> Configuration Properties) and select "All Configurations" in Configuration option.
This created the .dll for me
This happened to me after switching between branches in a project which have significant differences between them, I tried every solution from the web but non worked.
Finally, I had to delete my local project files and clone the project from the GitHub repo again, after that when I started the project, the project build worked without errors, and dll was generated.