Why does it say "Project with that name already opened in the solution"?

Question

I recently migrated a VSS database to TFS 2008. Using Source Control Explorer, I got the latest version of a solution with 12 projects.

When I opened the solution in VS 2005, two of the projects were not found. I am not sure why these two projects were not found, but thought it easiest to just delete and re-add them to the solution.

When I do this, VS gives me a "A project with that name is already open in the solution." The project doesn't appear in solution explorer, and is not listed in the .sln file.

Any ideas?

Obsequent

You may need to run VS as Administrator if IIS is involved. – Hebetic

VS as Admin was the fix for me. I had the project configured to use Local IIS as the hosting platform and did not start VS as admin – Smack

Answer 1

I had the same message... Seems like it comes from (.csproj) project file. Under first propertygroup there is a section named

<ProjectTypeGuids>...</ProjectTypeGuids> 

which generally tells Visual Studio to handle that project in some specific way. Some Guids can be found here.

First make a backup copy of that file. Then removing that section can help you open the project as usual project. As it seems that the Visual Studio thinks that the project is not the type that is specified in the ProjectTypeGuids.

Surprising

Tnx, you have just saved my day:) – Augustineaugustinian

Worked for me BUT note that you need to close VS and reopen. – Mantel

Worked for me in VS 2022 Community Edition. I restarted Visual Studio after editing the csproj file and the unloaded project was now loaded normally. – Pussyfoot

This is the only thing that worked for me (opening a .NET Framework 4.8 solution in Visual Studio 2022 Ultimate for the first time) – Guardian

13 years later and this answer is still valid. Thanks! – Anthropolatry

Answer 2

I had this problem and I was able to solve it using the following steps:

1. Remove the project from the solution.
2. restart visual studio.
3. add the project to the solution as an existing project.

Clavate

work for me too. but need to restart VS before step 3!! – Anticlimax

its worked, Thanks :) But can anybody share the reason for such a behaviour. – Heliopolis

Do not skip step 2 - it's essential. Maybe it's for cleansing the bad aura. Also, do not forget to add reference to the remove-and-add-back project. Or your main project won't compile. – Deponent

The accepted answer did not work for me, but this solution worked. I had this issue with my Winforms VS2015 project. The reason for my comment is that not only older versions of Visual Studio can have this problem, but new ones too and the solution is the same. – Silage

Simple oversight on my part, but I also had to make sure I was running as Admin as well. Before that, this did not work. – Saving

I tried removing <ProjectTypeGuids> first and my project changed to a generic type causing it not to run anymore. I reverted and tried this - and it worked like a charm. Try this FIRST. – Off

Answer 3

Before anyone tries tempering with their solution- and project files, figure if you may have project dependencies outside the solution, such as IIS - and you forgot to start Visual Studio in Administrator-mode

Babbling

This was the problem #1 for me; and the second problem was that the IIS section was configured to use https, and I didn't have the default web site configured for https - just changing it to http fixed it. – Kieffer

This solved it for me. Oddly, I only had this problem in 1 out of 6 projects in the same solution. The other 5 loaded well. Thank you – Carthage

Thanks! This is the only that worked for me specifically running VS on admin mode. – Wire

Fixed for me also. Check the output window shows the following message: "The Web Application Project <project> is configured to use IIS. You do not have permission to access the IIS configuration file. Opening and creating web sites on IIS requires running Visual Studio under an Administrator account" Why the dialog shown doesn't just say this I have no idea :shrug: – Ragin

To add to this answer, I also had to update my .csprog from <UseIIS>True</UseIIS> to <UseIIS>False</UseIIS> because administrator-mode Visual Studio could not start the site in IIS for some reason and that was blocking the project from loading successfully. Which was fine, because I wanted to use IIS Express. – Gainful

Answer 4

For me, the project not loaded was because it was configured to use IIS on the local machine and I needed to start Visual Studio as an Administrator.

Byblow

This was exactly my issue too! Running VS in admin mode solved the problem. – Steiner

Same here and I picked up on it because there was another error in the output window "The Web Application Project Web is configured to use IIS. You do not have permission to access the IIS configuration file." but that wasn't the error that popped up in the error message. – Hebetic

Answer 5

This did it for me:

1. remove the section <ProjectTypeGuids>...</ProjectTypeGuids> in each project
2. reopen each project, then save to overwrite the existing project file, finally exit
3. reopen the solution file
4. pray (optional)

Devonadevondra

I don't think 4. is optional when dealing with those issues. – Njord

#4 made my day. – Donica

#4 is a must. If not performed, forget about the first 3 steps. – Furrier

I opened the folder with VS Code, searched all files for <ProjectTypeGuids>. Removed that node from every project, saved, closed the solution, reopened the solution. Solved. Thank you for your contribution! FWIW I skipped step 4. – Sergius

For me, absolute pray was on optional. Thank you, it gave the solution. – Resolutive

Answer 6

If anyone uses AnkhSVN instead of TFS, it's also possible, that the .sln-file need the following lines:

GlobalSection(SubversionScc) = preSolution
    Svn-Managed = True
    Manager = AnkhSVN - Subversion Support for Visual Studio
EndGlobalSection

in the "Global" section.

Organometallic

Answer 7

Unfortunately I don't know the why behind the obtuse error message, I can merely provide what steps I took to get it to go away.

In my case, I had reconfigured my local IIS (<UseIIS> not <UseIISExpress>) and it was no longer hosting the URL that was in the csproj <IISUrl> field.

Editing the .csproj file in another editor and changing that field to the new URL, followed by closing and opening the solution in VS resolved the issue.

Homophony

This solved it for me. There was a clue in the output when opening the solution "error : The Web Application Project {ProjectName} is configured to use IIS. The Web server 'localhost:{portNumber}/' could not be found." – Honest

For me, the issue was the IIS section was configured to use https, and I didn't have the default web site configured for https - just changing it to http fixed it. (This after starting VS as administrator.) – Kieffer

Answer 8

Delete .suo file. Build solution. Add Projects.

Ringtail

Answer 9

I have to say that removing the section <ProjectTypeGuids>...</ProjectTypeGuids> could create some problems. In fact, such a section defines the type of the project and, if removed, could disable some features. For example, if your project was originally defined as Smart Device (C#), after removing the aforementioned section the on-device debug may not working properly.

Aubrey

Answer 10

Somehow VS 2022 doesn't create a virtual directory anymore. I had to manually create the website in IIS

Cuss

Answer 11

I got it in Visual Studio 2022 version 17.4.4. You may also see:

Error HRESULT E_FAIL has been returned from a call to a COM component.

when you try to reload your project.

One way to load the project (and deal with IIS directories later) is to edit the .csproj file and set UseIISExpress to true. Replace:

 <UseIISExpress>false</UseIISExpress> 

with

 <UseIISExpress>true</UseIISExpress>

Then you need to close your solution and open it again and the project should load.

Hartmunn

Answer 12

I would try hand editing the project/solution files, they are text and pretty easy to read. You can edit the file in notepad. To open up the file as text in visual studio you need to first close the solution. Then do file->open and select the sln file, but instead of hitting the open button, press on the right side where there is an arrow and select open with.. from there you can select source code editor (text).

Priming

Answer 13

I had the same problem when i migrated a website to a web app project.

1. Unload the web app.
2. Add the existing website.
3. Reload the web app.

Chapbook

Answer 14

The following worked for me when I moved a project running vs2010 to another laptop.

I removed exactly the following and it worked:

<ProjecctType>Guid of sorts</ProjectType>
<SccProjectName>Svn</SccProjectName>
<SccLocalPath>Svn</SccLocalPath>
<SccAuxPath>Svn</SccAuxPath>
<SccProvider>SubversionScc</SccProvider>

Semele

it worked for me, thanks - i just needed to close the solution and restart VS2005 in order for it to work after the edit. – Foote

Answer 15

For those looking for this while dealing with VSTO projects...

Be sure to have the Office Tools for Visual Studio installed in your machine before opening the project.

Donndonna

I (also?) had to install "Microsoft Visual Studio Tools for Applications" (it appeared to be for vsta at first but now VS wants to open the project) – Usually

Answer 16

I solved it by changing Windows' regional settings. Instead of "English (Europe)", I used "English (United States)". Others have reported similar behaviors with changing for example from "Russian (Ukraine)" to "Russian (Russia)", etc. -AlessandroSegala

Work For me.

Ref: http://answers.microsoft.com/en-us/windows/forum/windows_10-windows_install/customized-cultures-cannot-be-passed-by-lcid-only/26eb9d4b-7ddb-4774-8a40-7a7d84ba9277?auth=1&rtAction=1455534187354

Malar

Answer 17

In my case it was corrupted vbproj file. First line was missing:

<?xml version="1.0" encoding="utf-8"?>

After adding this line I had to close the solution, delete .vs folder and open again.

Ferrosilicon

Answer 18

I encountered this issue with web application projects. When I tried to reload the projects, the VS2022 output said something like :

"The project is configured to use IIS. Unable to find the server '{site_url}' on the local computer. Ensure that the local IIS is configured to handle secure communications."

Which is pretty clear. Indeed, in my case, this was caused by my website https binding that just vanished for no reason (it happened to me several times, looks like a bug with Windows 11 & IIS 10). Things got fixed when I got my https binding back (projects could load normally).

Polydactyl

Answer 19

I had the same issue in a .NET Framework project. I was using VS2022.

Before trying this please keep backup of the files you are editing.

Still unaware why this happened suddenly. But the following worked for me.

1. Remove the project from the solution list in visual studio
2. Go to the solution (.sln) file and open it in an editor
3. Remove the entries that you have for your project which can't be loaded.

Example : Remove the following that is right before GlobalSection :

        Project("{FCA04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Web", "Web\Web.csproj", "{5CA8CA45-47D0-4AC8-9BDF-2030B751CC10}"
EndProject

Also remove the followings from the GlobalSection :

        {5CA8CA45-47D0-4AC8-9BDF-2030B751CC10}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
        {5CA8CA45-47D0-4AC8-9BDF-2030B751CC10}.Debug|Any CPU.Build.0 = Debug|Any CPU
        {5CA8CA45-47D0-4AC8-9BDF-2030B751CC10}.Release|Any CPU.ActiveCfg = Release|Any CPU
        {5CA8CA45-47D0-4AC8-9BDF-2030B751CC10}.Release|Any CPU.Build.0 = Release|Any CPU

4. Close Visual Studio.
5. Open Visual Studio in administrator mode.
6. Add existing project.

It should work now.

Kun

Answer 20

In VS2022

1. Close VS.
2. Delete (or backup) the hidden .vs folder.
3. Open VS and solution.

Lycanthrope

Answer 21

In VS 2022 to open a legacy web project I had to:

1. Remove from Solution
2. Change framework version from 4.6.x to <TargetFrameworkVersion>v4.7.2</TargetFrameworkVersion> in from csproj
3. Remove <OutputType>Library</OutputType> from csproj
4. Close Solution and open it again (!!!)
5. Add project to the sln again.

Dogmatism

Answer 22

I had this problem too. I am sure that some of these solutions work for some people's circumstance, however, none of the solutions worked for my situation (which is more recent than this 14 year old problem). In my situation, I had recently gone through a rebuild of my PC. A project that once loaded on my older machine, no longer loaded under the new build. It turned out, I hadn't yet created the IIS applications (and appropriate folders) for those projects. The clue in my case was that only web application projects were not loading. So get those folders setup in your inetpub/wwwroot/#application# and it might start behaving once again. After setting up the folders, you may need to restart your IIS session.

Able

Answer 23

Basically you need to exit visual studio and start again as administrator, it should work.

Cyclic