VS 2015: Unable to start debugging. The startup project could not be launched.

[srkinyon]

After installing the new Asp.net Core 1 Tooling preview to VS 2015, created a new project from the template for .NET Framework. When running the project (Start button or F5), received the old dreaded dialog "Unable to start debugging. The startup project could not be launched...."

The startup project is selected and bold. It was this way when the solution opened and right-click "set" didn't help.

Other facts & symptoms:

• In the Debug menu, Start Debugging and Start without Debugging are both disabled.
• The new project builds successfully.
• The command line 'dotnet run' works and the site can be navigated to.
• Other projects still run in VS 2015 (both MVC & WPF) - they still work & can be run in debug. Only the new Core projects have this behavior.
• Tried multiple new projects without success. The problem appears to be with the template or other elements of the Core tooling.
• Ran VS2015 as administrator and not, both have the same results.

[sayedihashimi]

TFS: 224822
I've added this to our internal TFS, we will reply back here soon.

[srkinyon]

More facts & symptoms:

• F12/Go to Definition didn't work for WebHostingBuilder or other new Core constructs.
• References is empty but Dependencies is full. Again, compiles & runs successfully using 'dotnet run'.
• Was missing some patch, applied by way of the uninstall/change panel. The update didn't specify what version it was at or what it was going to.
• Fully uninstalled tool preview, rebooted, reinstalled. No change.
• Fully uninstalled & reinstalled Visual Studio & Tools preview, then reinstalled VS & Tools preview. Emptied %temp% along the way. No change.

Attached logs on reinstall as a zip.

dd_DotNetCoreTools__20160525095446.zip

[balachir]

@srkinyon can you check if Add/Remove programs has the entry for "Microsoft .NET Core 1.0.0 RC2 - VS 2015 Tooling Preview 1"? Also can you share a screenshot of your VS Help-About - is there an entry for "Microsoft .NET Core Tools (Preview 1)"? We'd like to check if everything looks to be installed properly.

[srkinyon]

Both screenshots show it is installed. Note that I had ASP.NET 5 RC 1 installed previously. I stood up a temp machine with a fresh install of VS2015 and the tool preview worked there with no issues. My thought is that the problem my main development machine is having is due to the prior RC 1 install.

[cilliemalan]

I'm getting the same problem on a brand new PC. Never had RC1 installed.

[barrytang]

Can you check if the startup project is set? The bold one in Solution Explorer.

[srkinyon]

From the original post, 2nd paragraph: "The startup project is selected and bold. It was this way when the solution opened and right-click "set" didn't help." I'm very confident this isn't a lack of reading instructions from the dialog box image I posted. ;)

[srkinyon]

This is unsolved in the latest preview 2 release. I'm unimpressed to say the least that I can't use the new ASP.NET with Visual Studio 2015. Not solved in the next release, no workarounds, no attempt to solve it really. So will this product only be marginally supported sometimes, like when the problems are easy?

[barrytang]

Hi @srkinyon, @BillHiebert looked at the issue and confirmed it is related to VS output window creation which isn't owned by my team. I am following up with the VS IDE team to see if this is a known issue and whether there is any workaround. Apologize for the inconvenience and I will update you as soon as I hear back from the VS IDE team.

[srkinyon]

Can you provide a work around? Or maybe a way to fully uninstall it? It appears it is manually altering something and it is surviving an uninstall/reinstall (I uninstalled the whole VS and it still happens).

I can't see this being an Output Window issue, but I'll take your word for it. The fact that the References are blank and the Intellisense isn't working would seem to indicate something isn't registered correctly.

[fabioes]

Try to uninstall all previous version of .NET Core and install the newer version...It works for me.

[vimception]

I'm seeing the same same problem. @srkinyon my workaround is currently to run VS15 as Administrator.

[srkinyon]

I uninstalled older versions prior to installed the newest version. And I tried running as Admin again - no change. It would appear a change happened on a system level and that change both survives uninstall and isn't impacted by security (at least for me).

[jdrobison]

@srkinyon, @langsweirdt: there's not a lot to go on for figuring out whether this is related to the Output window, but I have a few questions that may lend some clues:

1. Can you send a screenshot of your IDE when you're experiencing the problem?
2. If build is working, are you seeing build output in the Output window?
3. What's in the "Show output from:" dropdown in the Output window?
4. Do you still see the problem if you run VS in safe mode (devenv /safemode)?

[srkinyon]

#1 Attached.

#2 “If build is working, are you seeing build output in the Output window?”

• I see what looks like standard output with ‘Build’:
  1>------ Rebuild All started: Project: HelloWebFull, Configuration: Debug Any CPU ------
  1> C:\Program Files\dotnet\dotnet.exe build "C:\Projects_Testing\cli-samples-master\HelloWebFull" --configuration Debug --no-dependencies --no-incremental
  1> Project HelloWebFull (.NETFramework,Version=v4.5.1) will be compiled because project is not safe for incremental compilation. Use --build-profile flag for more information.
  1> Compiling HelloWebFull for .NETFramework,Version=v4.5.1
  1> Compilation succeeded.
  1> 0 Warning(s)
  1> 0 Error(s)
  1> Time elapsed 00:00:01.3121388
  1> (The compilation time can be improved. Run "dotnet build --build-profile" for more information)
  ========== Rebuild All: 1 succeeded, 0 failed, 0 skipped ==========

#3 “What's in the "Show output from:" dropdown in the Output window?”

• Only Build & Build Order while in Safe Mode.

#4 “Do you still see the problem if you run VS in safe mode (devenv /safemode)?”

• Just tried, not difference (see image).

[jdrobison]

Could you capture a dump of the VS process using Task Manager? (Let me know if you need detailed instructions.) Once you have it, could you share via OneDrive, Dropbox, etc.?

[srkinyon]

@MTBandolier Let me know when you've downloaded it. I didn't see anything in it that can't be public, but I'm going to remove it once you have it: https://www.dropbox.com/s/ctrghumoszbd2f8/devenv.zip?dl=0

[jdrobison]

@srkinyon, got it. Thanks!

And just to confirm, this dump captured the process when you're in the state where you can't start debugging?

[acrigney]

Running as administrator and uninstalling the RC2 version did not work for me.
Hopefully this will be fixed soon?

[taylorlowery]

Just uselessly chiming in to say that I'm having the same issue and I'm sad about it. I tried the same uninstall/reinstall/nuke it from orbit things seen above, to no avail :(

[SoulFireMage]

I've got this issue and all I did was start VS in Administrator as I needed that to run IIS express such that my colleague could access the test site from his computer.

[Joshuagollaher]

I fixed it, this was happening to me when trying to run a node.js project. I was messing around, and I went to Debug->Options->Projects and Solutions and turned show output window when build starts off.

[RationaleIT]

I'm also having this issue, although I am not sure what has caused it. It was working fine the other day and now it isn't. Windows did a few updates and I also installed the github extension for VS2015 and since then it seems to have stopped working. Have tried uninstalling and reinstalling VS2015 Tools Preview 2 to no avail. Any suggestions?

[RationaleIT]

So, just an update. Downloading the latest windows updates (Windows 8) and restarting the computer seems to have fixed the issue.

[gusmanb]

I'm having this same problem, but I'm on Windows 10 and it seems like it happened when the anniversary update has been installed, previous to that it worked for me...

Any ideas?

[gusmanb]

Ok, for me the problem was a recent change on the solution.
In my solution I have a framework I'm developing with two variants, one for .net core and other for .net.

It happens that a library project exists on both versions of this framework and the project name is the same, and even if the frameworks are on different folders it seems it was taking the wrong one.

The structure was like this:

-Solution's root
|
-----MyLib project (.net)
|
-----Core
.........|
.........|-----MyLib project (.net core)
.........|
.........|-----Test project (.net core)

I first tried to rename the assembly name and project name with no result, after that I removed the .net library and it started to work, but the reference was showing the old package name. I had to rename the library's folder and finally it set the correct reference name and after that I readded the .net library again and it still works.

The worst of all is that vs told me the compilation was correct every time I tried to compìle the app but it wasn't really compiling it I assume.

So it seems like here exists two bugs: .net core compilation (at least under vs) is resolving the wrong references and compilation some times even if it fails reports a correct result (or may be the app was compiling but the debugger could not start the program? not sure).

Cheers

[valterekholm]

Hello. I'm quite new in VS but I can share that I had this message too, but it got solved after help - and by removing to references that didn't belong in .net core... Identity och WebApiCompatShim. My mistake.

[leonardobaggio]

@valterekholm I've came across this error today, and solved by running VS2015 as Administrator.

I still have no idea why this happened.

[jkicha]

I am on Windows 10 with .NET Core 1.0.1 SDK 1.0.0-preview2-003131

This solved the above problem for me.

http://stackoverflow.com/questions/37612888/unable-to-start-debugging-the-startup-project-could-not-be-launched-vs2015

"All was solved by deleting CurrentSettings.vssettings".

[srkinyon]

Fixed! If there was a prize, @jkicha would have gotten it! Thanks for all the posts, this issue (as least for me) is closed. It is fixed just in time for VS2017....

[reticulan]

Getting this problem in WPF project on VS 2015 after changing russian language to english.

[NicoJuicy]

Run Visual Studio 2015 as Administrator and then open your project :)

[ze555]

easy solution for it
go >> C:\Users\username\AppData\Local\Microsoft\Phone Tools
delete folder CoreCon
start now your visual studio

[hadevnet]

it's very strange but just you need to run this commend :

• dotnet restore
  and restart visual studio.

it works!

[SimonCropp]

this still happens in VS 2017. can it be reopened

[barrytang]

To report new issues, use the Report a Problem tool. The GitHub Issue Tracker for the aspnet/Tooling repo is now deprecated in favor of the Report a Problem tool.

If you encounter a problem with Visual Studio, we want to know about it so that we can diagnose and fix it. By using the Report a Problem tool, you can collect detailed information about the problem, and send it to Microsoft with just a few button clicks. See here for more details.