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C# program won't start outside visual studio as a .EXE

I have created a small program in C# WinForms that runs fine when I start it in Visual Studio 2017. But when I build the solution and double click the .exe, nothing happens, no screen appears, even the task manager doesn't see it. No errors. It's like it doesn't do anything! My only guess is that I built it wrong because I used Nuget to install newtonsofts JSON.NET in the solution. Do I need to do anything differently or should just building the solution work?
[solved]
today i learned the difference between the bin and obj folder, thanks to everyone for helping

Based on your comment:
it is in the obj/debug folder of the project
It sounds like you're running the wrong .exe. The obj folder is used for temporary/misc. files from the build process (see What is obj folder generated for?).
Instead, you want to run the exe within bin\Debug, if "Debug" is the configuration you're building for. You can see which configuration at the top of VS.
Like others have also mentioned, make sure that Newtonsoft.Json.dll is being copied to that output directory as well. Programs and their dependencies need to be together, generally speaking. Otherwise, your exe will not know where to find the JSON code it needs to function.
99% of the time, you should pretend the obj directory isn't even there.
If that still isn't pointing you in the right direction, run the app from a command window. Any exception should get printed to it and the window will remain open for you to examine (and this has the benefit of not needing any additional logging or exception handling code to see this error).
For example, I wrote up a bad application that get a NullReferenceException in a method called Test that is called from Main. As you can see, the stacktrace is easily visible, even though my app has crashed (credit to ColinM for bringing this up originally).

I believe that there's a problem with the startup module. Follow the steps below
Open your Solution in visual studio
Double click on properties
Select output type to Windows Application
Make sure to set the startup object as follows
I hope it helps

I think there is only one reason
There is a command line argument predefined in Visual Studio. Your application uses this argument to be executed, without it, it closes itself too quickly and you even can't see your application opened.
Right click on your project in VS -> Properties -> Debug and see if there is a value in command line arguments

exe and their supporting files should be in the bin folder. Do not copy only exe from bin folder and try to run it. It is a good idea to write some exception code to get the detail.

For future reference, yet another reason (that I have experienced) can be
System.Diagnostics.Debug.Assert();
statements. In my case, the program executed normally when started from VS but when I run it by clicking its .exe (created in the Debug Mode) then it hung/freezed. No exceptions, no printed logs. Frustrating. Then I checked the Windows Event Viewer (Our true friend). It explicitly displayed the problem and the culprit was a Debug.Assert() statement.
The lesson learned again: Check
Windows Event Viewer > Windows Logs > Application
especially when your app hangs/freezes/deadlocks or when no app logs are available.

"Error while trying to run project: Unable to start program". Can run program only once. Then VS needs restart

I'm running my .NET 4.0 (C#) project in debug mode after I start VS2013. It runs just fine.
The second time I start it from VS, I get the Dialog box that says "Error while trying to run project: Unable to start program C:\path\to\file.exe"
The process is still alive in the Taskmanager when I dismiss the dialog box.
From Windows Explorer, I can run the program just fine. And after closing it, the process is gone too from the Task Manager.
A rebuild doesn't help.
Is this a common problem with a known solution?

I had an issue similar to this and I had to clear the component cache instruction can be found Here.
Hope this helps.

For my case, it cause by Platform target, you could force choose it to x86 or x64 which your project is:
Each Project's Properties > Build > Platform target

As I pointed out also here, the only solution that worked for me was to disable the ConEmu integration:
ConEmu → Settings → Integration → Default term → disable Force ConEmu as default terminal for console applications
Some users reported that it was enough for them to disable the Aggressive mode in that same settings tab; that wasn't the case for me though.

The topic is old, but this might help someone else.
So in my case I made a file in Visual Studio with .cp extension (accidentally deleted the last 'p') this made visual studio just "include" the the file and not mark it as a compilation unit, thus not compiling it, I looked the *.vcxproj file in a text editor and found out about this, so if you open the project file in a notepad or something just find your file at the bottom usually and change from <Item .../> to <ClCompile .../>

I was getting similar errors. I just had to restart visual studio. Sometime couple times a day.

I had a similar error and resolved it by cleaning the solution. Right-click the solution name in Solution Explorer and choose Clean Solution.

I found a solution here:
Please check "Use Managed Compatibility Mode" under Tools|->Options->Debugging->General.

I'm Brazilian, I don't speak English very well. I did this translation on google translator.
I know the topic is old, but it can still help someone.
I had this same problem in the following situation, I have a dual boot computer (linux debian 11 and windows 10). Inside debian, on my NTFS D disk, I created a folder to perform programming tests. After accessing that same folder with windows, I created a new project in visual studio inside that same folder that I had created in linux. The creation of the project went without problems, however when I tried to run the project (F5), I received the same error from this topic. I tried all the solutions I found on the internet, and nothing worked. I gave all permissions to my admin user and it still didn't work. Then I realized that even going straight to the folder where the application's executable was and clicking directly on it, I still received the access denied error message. So, I took the project out of the folder I had created in linux, and it worked. So, what I could conclude, is that because the folder where my project was was created in linux, for some reason, my windows didn't trust this folder, so it didn't allow running executables from inside that folder, even this one executable having been created by visual studio from within windows.

Just simply create a folder name as "projects" in c drive and copy paste the newly created project in it. Run the project by doing clean & Build or Rebuild method . It will work

open the folder which contains the solution in visual studio.
again, open your *.sln file by double clicking it inside the solution explore once opened try running the solution or rebuild the solution. once rebuild gets completed, it will open without error from next time.

My way of solving the error : error while trying to load project : Unable to start program and c:\Path\to\file.exe was simply by
First restart Visual Studio
Click the build icon
Select the rebuild option
Run the Program or Debug the Program

This was a weird one. Going to put what happened to me here because it might happen to someone else. Everything was fine with the app until suddenly after some fairly insignificant code changes I suddenly started getting this error. Visual Studio was compiling the executable just fine. But, the moment I tried to run it (either from Visual Studio or directly) the executable file would be automatically deleted right out of the Debug folder. Super odd--never seen anything like it. I began to get suspicious that perhaps an anti-virus or the OS was somehow identifying a checksum or some signature in the executable as "dangerous". Or perhaps some obscure compilation bug was corrupting the executable. So on a hunch I made another innocuous change (added a couple of lines of code to color code some text in a rich text box) and the problem went away.

Locking files when building in Visual Studio 2010

Hello there, Stackoverflow.
Recently, when I've been programming in Visual Studio 2010, I've been getting the problem with VS locking the bin/Debug/(ProjectName).exe file when trying to build and gives me the error below after trying to build the project 10 times:
Unable to copy file "obj\x86\Debug\TileEngine.exe" to "bin\x86\Debug\TileEngine.exe". The process cannot access the file 'bin\x86\Debug\TileEngine.exe' becuase it is being used by another process.
The problem appears when I edit the source and then try to Debug.
I've checked using different programs, and the only program using the file is Visual Studio.
If I wait for about 10 minutes before trying to build, it seems to work properly, but when trying different things, it isn't good needing to wait 10 minutes before trying something.
I've tried different solutions both on this site as well as everywhere I can find on Google.
Some solutions I've found, but haven't worked for me
Solution 1 - Using a pre-build script
In some different questions here on Stackoverflow, I've found one solution being that you go into Project Properties > Build Events and then in the Pre-build event command line add:
if exist "$(TargetPath).locked" del "$(TargetPath).locked"
if not exist "$(TargetPath).locked" move "$(TargetPath)" "$(TargetPath).locked"
This made it possible for me to build the project one more time than I usually could, but when editing the code again, and then building, the same error appeared.
Note: Trying to build a release instead of a debug build seems to break the pre-build script and it exits with the code '1', which seems to make VS unable to build properly. Removing the pre-build script makes it work like "normal" again, still with the same error though.
Solution 2 - Running Visual Studio as Administrator
This is another solution I've found, but havent worked either for me, so I assume that Visual Studio already have all the permissions required and running as Administrator doesn't actually make any difference.
Solution 3 - Changing the AssemblyVersion
In this question, Visual Studio build fails: unable to copy exe-file from obj\debug to bin\debug, I found another solution that included changing the AssemblyVersion, in the Properties\AssemblyInfo.cs file, to "2.0.0.0".
This, however, haven't made any difference whatsoever for me.
Solution 4 - Closing UserControl designers before building
According to some different answers here and there on the Internet, Visual Studio apparently uses the built project executable to render the UserControl designer(?). In my case, this is probably not it, though, since I use XNA mostly and it doesn't use the UserControl designer.
Solution 5 - Cleaning up resources when application quits
This might be a solution that I have failed to implement properly. I'm just thinking though, that if this is the solution, how come I haven't been required to do it before. I assume XNA unloads everything that gets loaded through the Content pipeline, therefore this solution wouldn't' make any real sense.
If there is anyone that is able to spread some light on this issue, it would be really awesome, as it is stopping me from programming anything really, because I don't like waiting for 10 minutes because I've made a 2 second change all the time.

I've run into this problem a few times myself.
Mine might not be from the same cause as yours, but I'll tell you what went wrong with me and how I fixed it, hopefully it'll be helpful to you.
Basically, my program never fully exited properly, even when it appeared to. It would continue to run, and thus continue to lock down the file.
A quick dirty fix I used initially (and a way to prove if this is the case) is:
Open Task Manager (Ctrl-Alt-Del)
Click Processes tab
Look for your program's name (TileEngine.exe)
Note: There will probably be name_vshost.exe (TileEngine_vshost.exe) That's a VisualStudio thing, ignore that, it's not relevant.
If you find it, it means your program hasn't actual exited fully.
If it's there, click on it and press "End Process"
So if it's there, then for some reason, your program didn't shut down, like mine did.
Often, this is from a thread being launched and forgotten, or an Async task that never completes, or something like that.
Make sure in your OnExiting(..) void function that you kill all running threads.
If your program is still running despite best attempts to close all threads and other blockers, you can use the very dirty bad method:
In OnExiting(...) run the code "System.Diagnostics.Process.GetCurrentProcess().Kill();" - this will taskmanager-style forceshutdown the current process... this is only as an emergency I-can't-make-it-work-any-other-way method.

I think I found the solution myself.
In the Project Properties, "Enable the Visual Studio hosting process" wasn't checked. Checking it seems to have fixed the problems, at least for now.
Got reminded of it from mcmonkey4eva's post. So thanks for that =)
And thanks for the other replied I've got. Stackoverflow is awesome!

Have you checked if any files are being blocked by your firewall? When I switched to the full version of Avast I find I have to disable the File System Shield It loves to remove my executable files when I try to run my visual studio projects.
I had problems when upgrading to VS2012 Professional. (SDK, .Net, Visual C++ Redistributable package)
ENSURE ALL OF THESE ARE COMPATIBLE WITH THE CURRENT VERSION OF VS YOU ARE USING
What I did, was I ended up uninstalling EVERYTHING that was associated with both Visual Studio downloads. If you are able to remove and save your project files elsewhere and then bring them back. Go through all your program files to see if there is anything hidden in the wrong folder and check your C drive.
Which meant downloading and reinstalling (fresh):
I think if you clean out your program files, it should be ok. I wouldn't recommend going into your register unless you are very sure of what you are doing. IF you have already made changes to the register then we'll have a look at that and other options (if this doesn't solve your problem).

Try removing the readonly check from your solution by unchecking at the folder level.

I ran into this problem and in my case was due to having bin included in the solution; as soon as I excluded the bin folder from my solution the problem went away.

Nothing helped, not prebuild commands, neither designers closing, but I figured out a way that helped me, just changing from debug to release and vice-versa releases locked files and you can delete them without closing the IDE.

I regularly get this problem if I switch from Debug to Release and then immediately F5 to compile. Crazy as it sounds, waiting for, say, one minute after switching between modes will prevent this.
If it's locked, the only solution is to close Visual Studio and re-open.

I solved this problem organizing my resources on solution. I noticed this error when I put some images on my application at the same solution folder.
So,
I'd removed all images and resources from app, save without it.
Moved the images to outside Solution folder.
Open the solution and add this images again, using "Import" button at controls.
If you will try this, remember to do with Application Icon, on Project Settings.
Now, everything is working fine for me.
I hope it helps.

You need to disable Windows Indexer as it locks up the file
Follow this Guide how to disable

In my case the problem seem to be caused by the remote debugger. It starts on local machine when you compile with "x64" option. Try to change the project setting (properties/buid) until you reach the final version.

Change Build Platform target from x86 to Any CPU.

visual studio C# locking .exe file

I am working on a gui app written in C# using visual studio and I am running into a really annoying bug where when I make changes to the application, it debugs correctly the first time I try to debug it, but when I try to debug the application again I get an error say that it can't copy an exe file from the obj directory to the bin directory.
Restarting visual studio fixes this.
It's really annoying to have to restart all the time though. There seem to be a number of posts online about this, but no one seems to have found the solution. Has anyone here been able to resolve this?

try VSCommands 2010 extension.
When you get the error again righ click on the message in error list and click 'Apply Fix' from context menu. This will tell you which process sits on the file and allow you to terminate it.
In a longer run, it may be that you have a background thread running which doesn't terminate when application finishes.

I have the same problem. I found in another thread (can't remember which) that for some unfathomable reason, you can change the assembly version declared in your AssemblyInfo.cs files from
AssemblyVersion("1.0.*")
into
AssemblyVersion("1.0.0.0")
Or some other explicit version, and the problem goes away. This worked fine for me. However, I would like a solution that would allow me to use the wildcard version as well. Or an explanation of why the assemblyversion causes the file to be locked.

is this a service? you may have to installutil -u prior to recompiling

In my case it was the Anti Virus software Avira antivir. When I added the publishing folders in the exceptions the problem went away.
Avira usually takes a long time to scan stuff in the background, apparently locking exe files before they can be overwritten. After the scan the file is unlocked. When my develop/test cycle is less than 30 seconds (which it often is) it will trigger this error after retrying 10x.

windows form dont start on other machines and process can't be closed

I've got a problem with my windows form application.
I wrote a simple program that can create .VTF / .VMT files out of .TGA files and can generate a .QC file and also compile this all with a .SMD file into a prop for the sourceSDK (Hammer Editor). So i can use this to bypass the incredible annoying task with compiling custom models for a map in Counter Strike.
Previously i could compile my form (same with other applications) and send it to someone so he can use it. This time it compiles normal and works fine on my system, but after i sent it to my friend it didn't start. He clicked at the .exe and his explorer.exe froze. After some time his explorer came back but he couldn't move or delete the file.
He also tried to restart his system, but afterward it still refuses to delete the file and then bluescreen. (The bluescreen said something about an Errorcode = 0xc000021a)
An other friend tried to start the .exe too, but he got the same problem with the explorer ...
I use Visual Studio 2015 to write and compile my code. My target Framework is .Net 4.5.2.
Does someone know how to solve this problem?
What further information do you need?
Thank you for your help
Greetings
Marv
EDIT #1: I think the bluescreen isn't that important for that problem.
We tried it again with serveral .NET Versions and it won't work at all.
The funny thing is that i sent him the whole Visual Studio project and told him to compile it on his system. The debug version in Visual Studio works fine but if he wants to start the release.exe in the subfolder /bin/release/ the same problem occurs..

Ok, i found the solution to this problem with some help from here:
C# exe not starting on Win7 build computer
and here:
Executing the Visual Studio created *.exe does not open a window and the process can not be terminated
He only has to turn off his avast antivirus...
EDIT #1: I found out that disabling the "Deepscreen" feature in Avast is enough to solve this problem.
Thank you for your help