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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?

Peter Mortensen
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nbon
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34 Answers34

284

Have you tried to delete the Your_Solution_FileName.suo file?

The .suo file should be in the same folder as your .sln file, or in the .vs folder for newer versions of Visual Studio. The .vs folder might be hidden.


Update for Visual Studio 2017
In VS 2017 the .suo files are located in a different folder: you can find the .suo file in YourSolutionFolder\.vs\YourSolutionName\v15\.suo

The .vs folder is hidden, and the .suo files is a file without name, with just the .suo extension.


 
Explanation

The .suo file contain various information like the opened files list, and some preferences that are not saved in the solution file (like the starting project) and other things.

Normally you can delete the .suo file without problems. You might have to set the StartUp Project for your solution afterwards.

Just to stay on the safe way, you can rename the .suo file, and then retry to start the solution, to see if this help.

In my experience sometime VS crash on start because there is an error in some source code, and due to that error VS can't compile the code, and then crash because without compiled code it's unable to show form in design mode. In this case, deleting the .suo file will solve the situation because it reset the open files list, so the solution can start up without opening/showing any files.


When deleting the .suo file doesn't works
Here's a list of other things you can try when deleting the .suo file doesn't resolve the issue:

  • Restart the computer
  • Clean Windows temp folder
  • Clean the solution from the IDE (Menu\Build\Clean Solution)
  • Clean the solution manually (delete the compiled DLL/EXE in the /bin/ folder and empty the temporary files that VS create during the build process in the /obj/ folder (each project that compose the solution has these folders, so clean them all))
  • Try to open each single project that compose the solution 1-by-1 and build it, to understand which is the specific project that generate the issue
  • Understand what is the change/edit/modification that triggered the error, and undo it (source control tool can help...)
  • If you have custom controls: check the code in the constructor. The VS IDE will call the constructor of your custom controls even at design time, and weird things can happen (at design time some properties dont works, your connection string probably isn't populated...)

As a last resort...

  • Try to install any VS update
  • Try to disable VS extensions (if you installed any...)
  • Try to update any external DLL/Control referenced in your solution
  • Try to update Windows
Max
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  • @sergiol have you tried to disable any visual studio Addins you may have installed? Sometime they can crash the IDE – Max Apr 24 '15 at 18:44
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    @sergiol Try removing all .suo. I delete the .suo that exist at the top of the solution folder and didn't work. Then I search one in a hidden folder "\.vs\ci-ucsp\v14" and finally works. – Erick Asto Oblitas Aug 11 '15 at 11:10
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    In Visual Studio 2015, the solution was to delete the .user files that go along side the .xproj file. – sixones Aug 28 '15 at 16:01
  • Deleting the .suo file inside the .vs folder did not work. Also, I did not have any .user file to delete. – Jorge Cabot Nov 01 '16 at 21:37
  • @Jorge Cabot Other things you can try, in no specific order: restart the computer / delete windows temp folder / clean the solution from the IDE / clean the solution manually (delete the compiled DLL and the temporary files that VS create during the build process) / Understand what have you done to trigger this error, and undo it / try to open the single project that compose the solution 1-by-1 and see if it's a specific one that give you problem / If you have custom controls: check the code in the constructor, the IDE will call it in design time – Max Nov 01 '16 at 22:00
  • @Max After installing an update to VS2015 and performing a restart the error is now gone. Thanks. – Jorge Cabot Nov 02 '16 at 01:44
  • My comp crashed due to a power outage, and when trying build/rebuild/clean after booting back up again I got this error. By manually removing the EXE and cleaning out the obj-directories fixed it for me. Thanks a lot! – Ludricio Mar 07 '17 at 11:27
  • Repairing Visual Studio solved the problem for me. I had this issue with VS2008 (yes, 2008!) after installing VS2017 (but this could be unrelated). – arni Mar 13 '17 at 17:32
  • Was happening to me only on the Release configuration. Deleting *.suo did not solve, but closing VS, delete *.suo and starting VS again did the job. – sergiol May 03 '17 at 16:10
  • This happened to me specifically with VS2015 while I was working on an SSIS package. I just restarted VS2015 and it solved my problem. – dyslexicanaboko Jul 11 '17 at 21:05
  • Happened to me in a CMake-generated project for VS 2017 (version 15.3.5). All of my projects built in Debug, but in Release, some built while others did not, giving the terse "unspecified error". I deleted `build\.vs\.suo` and then it built in Release. – metal Sep 29 '17 at 18:56
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    I arrived here seeing similar problems, no answers here worked. I just found my problem was caused by the fact that my solution is on my onedrive, Onedrive was updated and has a new feature called files on demand. This feature causes similar problems as described here. More details can be found here. https://developercommunity.visualstudio.com/content/problem/134518/visual-studio-does-not-like-onedrive-files-on-dema.html – Leon Degeling Apr 12 '18 at 20:53
  • Deleted the .vs file did it for me. – gharel Feb 02 '23 at 15:56
118

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

Update: Visual Studio 2017 apparently as well.

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...

Tom Stickel
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    This is a horrible anoying bug (the one thats solved bu this) a way of detecting the issue without actual trying to check is that the output window is not displaying (no output window == restart VS to fix). – Thomas Andreè Wang Jan 22 '16 at 13:45
  • I still prefer vs 2013 for some things like Nuget and some various TFS online connections and various areas of stability. Overall vs 2015 is fantastic, but certainly not without some issues. – Tom Stickel Jan 29 '16 at 17:37
  • I had another issue with VS 2015 the other day in which I could not get the localhost page to load. Fiddler was making tons of calls to something that I hadn't seen before. Not sure why, but me and another developer tried all sorts of things before I decided to try closing VS 2015. Then it worked fine on re-opening it. A little annoying , but no turning back from vs 2015 at this point ( sp1 is installed too) – Tom Stickel Mar 10 '16 at 21:07
  • I had VS 2015 Update 2 on a computer and suddenly I could not create NEW web application ( console apps etc.. i could) I was spending too much time trying to figure out the problem, I ended up doing a Repair via kicking off the VS 2015 plus update 2 bundle ... very annoying as reboot and other things did not fix it. - Just another issue I had that I figured I would add to comments. ( I did install vs 15 preview on that computer so I wonder if that install caused the problem ) . – Tom Stickel Apr 26 '16 at 20:23
73

VS 2015 -> Deleting all the files in the ComponentModelCache worked for me:

C:\Users\**username**\AppData\Local\Microsoft\VisualStudio\14.0\ComponentModelCache

Niels Filter
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    You can also look at the Microsoft.VisualStudio.Default.err file in that directory to determine what might be causing the issue. – Chris Lunt Mar 29 '16 at 17:51
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    @ChrisLunt That suggestion showed an Extension that was throwing errors. Removing just that solved it for me. – Boggin Jun 06 '16 at 10:42
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    Didn't work for me, deleting this files has absolutely no effect. Also, no additional lines appear in `.err` file when I see the issue. – Aleksei Petrenko Jan 08 '17 at 12:19
  • Thnx. It worked perfectly for me. Deleting .suo file and all other sort of things are not working. This is the perfect solution. – sapatelbaps Feb 05 '19 at 15:55
19

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.

QAZZY
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    I removed all of the sites in the applicationhost.config and was then able to reload the project. – Scott Munro Feb 26 '15 at 12:54
  • Yeah, I just had this problem when I switched git branches on the solution. Couldn't build, couldn't debug, nothing. Deleting the *.user file did it. – Kristian Apr 07 '16 at 08:15
  • I had a WIndows crash and VS (2019) managed to write null's out to my .user files -- and a few csproj files as well. Deleting the .user (and reverting the .csproj) files fixed it. – bmiller May 19 '21 at 19:30
12

For me, this issue was being caused by conflicting <site> configurations in the following file.

C:\Users\smunro\Documents\IISExpress\config\applicationhost.config

I edited this file to remove all of the site elements within the following element. You might want to be a little more selective and try to identify the site that is causing the conflict and remove just that.

<configuration><system.applicationHost><sites>

Note that I left the <siteDefaults>, <applicationDefaults> and <virtualDirectoryDefaults> elements there.

When I reloaded the project, a new <site> element was created automatically.

Scott Munro
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    That's more like it. The weirdest thing was, it errored in VS2015 but went through fine in VS2010.. :S Oldie but goodie? :) – army Jul 27 '15 at 15:02
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    If you're using Visual Studio 2015, then delete the applicationhost.config file out of \.vs\config\, this worked for me, because I had messed with the bindings. – Richard.Davenport May 26 '16 at 20:09
7

Make sure your Output Window is visible before hitting the F5 button. If you have your Output Window maximized, occasionally Visual Studio does not re-open the Output Window when you restart it.

Simple fix: 1. Restart Visual Studio 2. BEFORE building a project, use View->Output Window

Now when you build, it should work.

(I'm pretty sure deleting .suo and .user files only works because it resets Visual Studio to its default layout, which ensures the Output Window is visible.)

HiredMind
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  • This seems to be KEY to a working solution! I certainly didn't intentionally close the Output window and didn't even think to look and see if "Output" was there. Whatever the underlying issue may be the missing output window was part of the problem. NOTE: in my case View-> Output (ctrl+alt+O) was not enough to cause the window to appear, I had to THEN restart Visual Studio 2015. – Cos Callis Mar 12 '17 at 13:59
  • Yes. If you try to do Ctrl-Alt-O or View->Output after doing any operation that tries to write to the output window (e.g. a build), it's too late - you'll have to restart. – HiredMind Mar 13 '17 at 13:43
5

Run eventvwr from the command line to see if it has recorded any Application errors.

This might give you an actual error message that is more useful.

munnster79
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3

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.

Peter Mortensen
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Emmanuel
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3

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
チーズパン
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Stefano Nepa
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3

I had same error. I couldn't open any class and component of my solution. I deleted the ComponentModelCache and tested any other solutions.. but no result. Finally it helped me: Just CLOSE YOUR VISUAL STUDIO AND AGAIN OPEN IT!

Elnaz
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2

I removed an old project from the solution, after that the error occurred. I had to open the .sln file in notepad and delete the .dll reference tot he old project that I removed. After that it worked.

Christo Carstens
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  • I had a similar issue. The SLN file had a web site (not a web project), which was referencing a project which was removed from the solution. In my case I just re-added the missing project and all is well. – Mr. TA Aug 24 '16 at 22:57
2

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.

2

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.
1

"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.

Martin Connell
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enter image description hereRestart the visual studio as Admin will work on in many cases.

Ishwor Khanal
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1

The error can also happen if you're in the folder in Windows Explorer or another app as you try to delete it from VS or have the file opened in another app. Windows has the habit of locking folders and files, especially on networked machines. It is possible to break the lock by using Process Explorer occasionally, but the simplest thing to do is to get out of the folder or close the file in question.

Kxmode
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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.

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

Andy Li
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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!

Peter Mortensen
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Ian Grainger
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0

If you are using Visual studio 2015 and working on ASP.NET, create a new website, copy the previous files into the new site and build your site. Your old project is still referencing some old startup parameters.

  • This is a very extreme solution. Before you use this solution, try other solutions described in this thread. The first thing that sometimes Works (at least for me) is to close and re-open Visual Studio. – pocjoc May 31 '16 at 14:50
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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
Sri Murthy Upadhyayula
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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.

tk26
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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.

CesarB
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Restarting Visual Studio solved my problem :)

Peter Mortensen
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cahit beyaz
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  • Yes, that is what I said in 2015 . https://stackoverflow.com/questions/9079466/visual-studio-popup-the-operation-could-not-be-completed/33009291#33009291 – Tom Stickel Dec 14 '18 at 08:42
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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.

hydrix
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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.
Pabitra Dash
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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

Dan
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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.

sijovw
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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.

spadelives
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None of the solution above worked for me. But following did :

  1. Open the current folder in Windows Explorer
  2. Move the folder manually to the desired location
  3. Open .csproj file. VS will then automatically create the .sln file.
Sukhi
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I had similar problem in iOS project in vs 2019,it's running on VM in Mac, I close and restart the visual studio, the issue was gone

Adithya
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Execute dotnet --list-sdks in CMD window and check whether your global.json file's (which is in hidden and stay at the root of solution) version matches with a version you have installed.

Heshan
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I just had this in VS22 when trying to run, I could open and build fine otherwise, so technically a different issue from the OP, but since this is the first thing that comes up in Google I wanted to comment.

My issue was that somehow my project filters file added a new entry which was invalid. Since I was using an Unreal project this was complicated by the fact that the project and filters are generated and not checked into source control.

If you have this issue, see if you have any weird entries in your .vcxproj.filters file.

For Unreal projects this will be located in \Engine\Intermediate\ProjectFiles\

-1

I restarted the computer, and it's gone.

Kai Wang
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