.net - vs2017 - Visual Studio popup: “the operation could not be completed”

vs2017 build the operation could not be completed (20)

When I try to open a project, local or on a Team Foundation Server (TFS), I get a modal window telling me that:

The operation could not be completed: Unspecified error

Or the same message, but with "Class not defined.." instead of "Unspecified error".

These errors started happening earlier today when I tried to check in some of my work to the team foundation server. I have tried using Visual Studio 2008 on the same computer, but I still get the same error. I've also googled for it but none of the solutions seems to help me.

I have installed the latest updates from Windows Update as well.

Any ideas?


"The operation could not be completed" error can also be caused by a C++ project referencing another project that no longer exists in the solution.

Normally, when you remove a project from a solution, Visual Studio removes any references to it from other projects in the solution.

In my case, however, I was sharing projects between solutions hence a bad project reference managed to sneak in, and deleting the bad references fixed the error.

Using Visual Studio 2012.

Restart the visual studio as Admin will work on in many cases.

For Visual C++ projects, this can be caused by an improperly formatted vcsproj.filters file.

In my case, someone had performed a manual branch merge and didn't merge the filters file correctly. Visual Studio still loaded and built the file without any warnings, but would give the 'unspecified error' warning whenever trying to add or remove files from the project.

Scan your vcsproj.filters file for any duplicate entries or lines that look like this and remove them. Close and reopen the project.

<ClInclude Include="..\..\path\to\sourcefile.h" />

Visual Studio Enterprise 2017

For me it was because I'd added an entry to bind the site in IISExpress to a specific IP address, and my IP address had changed. I got a clue from the event log.

Hope this helps someone!

For this problem, I resolved it by deleting the .user file which contains the Visual Studio Project User Options. This File can be found in the same place where your .sln file is located. Also, after deleting this file from the project make sure to reload your solution in order for it to take effect.

Go to Run and type "inetmgr", i.e IIS is opened and in the right corner Action window, select option change ".NET Framework version". Change it.

After that, reinstall your Visual studio 2010. It works on my computer, and that's why sharing.

I deleted all .suo and .user files and restarted VS 2008. But it didn't worked for me. The following steps worked for me.

Open project file (.csproj) in notepad.
Removed all configurations from <Configurations></COnfigurations> tag.
Then add one by one configuration and reload project in VS.
Build the project or view project properties.

I had a similar problem on opening Razor Views

  • I logged on to my Azure account which was asking to re-enter my credntials.
  • Restart VS 2015 Update 1

I had to remove a webproject. There was an old referencing DLL file inside, and I had to clean that webproject, and then it worked.

I ran into this same problem but deleting the .suo file did not help. The only way I could get the project to load was by deleting the "Your_Project_FileName.csproj.user" file.


I ran into this problem again a few months later but this time deleting the "Your_Project_FileName.csproj.user" file didn't help like it did last time. I finally managed to track it down to an IIS Express issue. I removed the site from my applicationhost.config and let Visual Studio recreate it, this allowed the project to finally be loaded.

I think StyleCop is the reason of the this issue. So,

  1. Close VS.
  2. I removed all StyleCop.Settings and StyleCop.Cache files in all solution projects.
  3. I removed also all projects *.csproj.user file.
  4. Restart VS.

I was upgrading to .NET4.6 from a 3rd party app (unity3d). I would get this message when I tried to reload the solution when it wouldn't load on startup. My solution was right clicking the solution and selecting "install missing features" which prompted me to download what I needed. The download on the popup didn't work so I just installed the .NET targeting pack for what I was on (4.6) and this fixed it.

In my case, 'Silverlight 5 SDK' was missing and so my silverlight projects are not getting loaded. While trying to reload project it shows “the operation could not be completed” message. Once i installed, problem is solved.

In our, the problem appeared after making changes in Debug -> myProject Properties -> Web, specifically changing the project URL and then closing VS. Upon reopening, VS had trouble parsing the new URL and so threw the error. Unfortunately, further configuration through the VS UI was not possible since the project won't load.

Since the file configuration changes are persisted in the myProject.csproj.user file, which lives in the project's root folder, the problem was easy to correct by simply removing the myProject.csproj.user file. At that point the project would load and the user file was then regenerated when the project was next run in debug mode.

Note, the project URL in the regenerated file had to be changed from the default http://localhost:58995 to the original https://localhost:44302 before the entire application could be accessed since we have the app locked down under SSL. Your ports may be different. This was done through VS under Debug -> myProject Properties -> Web after running the project.

No more .SUO files, but deleting .user files works. FYI: I am debugging Silverlight project

Restarting Visual Studio solved my problem :)

Solution: I was getting this dialogue when trying to build/rebuild/clean my .sln. To fix it I needed to stop the IIS site bound to the application and restart visual studio. (Then start your site again).

How I discovered the cause: Seems this is a pretty generic message for a wide range of issues, I ended up tracking down my particular issue to a few locked files by IIS with the event logs.

The solutions for deleting all sites are kind of a "Nuke it from orbit" approach which should be used as a last resort.

Sometimes it is just a matter of closing Visual Studio 2015 and then open again.

I have had this happen on a few machines.

This does happen

"Have you tried to delete the "Your_Solution_FileName.suo" file?"

Also computer crashing like e.g. power outage etc...

Applies to Update 2 and Update 3 as well as fresh base without any updates...

While working on VB.Net projects in Visual Studio 2005, I have faced this issue many times. Usually, disabling the 'Enable the Visual Studio hosting process' option in the application's debug properties solves the issue for me. Usually, when the hosting process is enabled, calls to certain APIs can be affected.

To un-check this option, you need to follow the steps below:

  • Right click on your project in the Solution Explorer
  • Select properties
  • Under Debug tab, you would find a check box option for Enable the Visual Studio hosting process. Un-check this option.
  • Save your changes

Worked for me after I closed Visual Studio (2015 Community Edition), opened it and opened project again.Had Happened to me because I was using this project as a dependency in another project and it was opened in another instance but the changes were not imitated.