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I just downloaded Visual Studio Code and my Intellisense is not automatically working.
The two settings that control this seem to be set correctly:
"editor.quickSuggestions": true,
"editor.suggestOnTriggerCharacters": true,
I do get an Intellisense menu when i start typing and press "CTRL + Space", but this gives me a list of everything and not things specifically for my object.
What am i doing wrong?
If you have a workspace and for some reason have multiple folders you may need to 'help' omnisharp a bit. I initially had a big project and added a solution for it further on - ending up with TWO workspace folders (one to a startup project and one to the solution). After composing that setup I experienced only the first project to have intellisense working.
Solution to get intellisense working was to make sure omnisharp worked its way from the solution instead of the project:
Ctrl + Shift + p
Write "OmniSharp: Select Project" and press Enter.
Choose the solution workspace entry.
Inspiration gotten from 'swaner':
https://github.com/OmniSharp/omnisharp-vscode/issues/1889
Visual Studio Code's more advanced editing features (IntelliSense, refactoring tools, etc.) only work in C# files if you have a project.json file or *.sln file that VSCode is aware of. Open the folder (i.e. open the File menu and click Open Folder...) with the *.sln file or project.json and VSCode will attempt to find all project/solution files in the folder. If there are multiple projects, you may need to select one from the projects button on the right side of the status bar (bottom of the window).
From the VSCode website:
Selecting a project.json-file is opening a DNX-project and VSCode will load that project plus the referenced projects
Selecting a *.sln-file is opening a MSBuild-project. It will load the referenced *.csproj-projects and sibling or descendant project.json-files but no other project files that are referenced from the solution file.
Selecting a folder will make VSCode scan for *.sln and project.json files and VSCode will attempt to load them all.
If you are start your project with c#, then some time you haven't download extension.
Process by written
Ctrl + Shift + p.
Write "OmniSharp: Select Project" and press Enter.
Choose the solution workspace entry.
Then enable the c# extension for "OmniSharp : Project".
Process by image
Downgrading to 1.23.9 of the C# VS Code extension fixed the intellisense for me. So if nothing else is working for you, perhaps try installing an older version of the extension (doesn't necessarily have to be that exact one I mentioned). You can do this by selecting this option in VS Code:
As of the 0.5 version I have found that I need to close and re-open my working files to get some new intellisense information to start working for my own files. This usually happens after I have a file open that needs to use type information from another file I just created. Until I close and re-open them (within the editor) the intellisense doesn't always work.
Hopefully this is something that'll get fixed as the app matures.
Inorder to make the intelligence working, the Visual Studio Code extension OmniSharp should be there along with Mono. When you open a project/solution folder, the OmniSharp gets the project dependencies from either project.json or from the dotnet solution file (if the project/solution created with other versions of visual studio).
So, when you look at the omnisharp's output window after immediately opening the project/ solution folder, you may see the following lines
Starting OmniSharp server at 2017-9-18 09:26:44
Target: /Users/{username}/Source/{Your Solution Folder}/{Your Solution
file}.sln
OmniSharp server started wth Mono
Path: /Users/{username}/.vscode/extensions/ms-vscode.csharp-1.12.1/.omnisharp/run
PID: 5808
post that, you may see couple of lines coming up like below,
[info]: OmniSharp.MSBuild.MSBuildProjectSystem
Update project: {Your Project1 Name}
[info]: OmniSharp.MSBuild.MSBuildProjectSystem
Update project: {Your Project2 Name}
....
they mean that your projects are getting recognised by OmniSharp Extension.
If you get any error message informing you about timeout, please get into the settings of the Visual Studio Code, and add a configuration override like the one below:
"omnisharp.projectLoadTimeout": 200
I know it is too long to wait for 200 seconds. But don't worry, this won't stop you anymore working with project files. But, remember that the IntelliSense will be automatically available once all the projects in the folder are successfully loaded.
Feel free to extend the Timeout setting since it will help you getting intellisense even-though you are not getting it immediately.
Here is another link with the same solution: https://github.com/OmniSharp/omnisharp-vscode/issues/1585
Hope my information helps you! Enjoy your VSCode!
This case was for an existing project that was working fine before. Opened via the vs code "recent" history.
For dotnet core. I opened my project's *.csprog file, made no changes, and saved it via the vs code editor.
As soon as I saved, all of the intellisense stuff starting working again in my other files within that project.
Another troubleshooting strategy to try if none of the above works out is uninstalling Mono, which is unnecessary anyways if you're using .NET Core. I also experienced a sudden disappearance of Intellisense after pulling changes to one of our enterprise repos that included an upgrade from ASP.NET Core 2.0 to 2.1. Strangely, at the same time, Intellisense was working fine in another C# project repo running ASP.NET Core 2.2.
For the project in question, I was puzzled to see successful logs for each reboot of the Omnisharp server as well as perfectly clean builds and runs. The puzzlement increased as I compared these Omnisharp logs to those from the 2.2 project and found them effectively identical.
Upon uninstalling Mono, the one detail that changed is how Omnisharp started. Now it boots up from a shell script located at ~/.vscode/extensions/ms-vscode.csharp-1.19.0/.omnisharp/1.32.18/run. Previously, Mono itself was booting the server from the executable at ~/.vscode/extensions/ms-vscode.csharp-1.19.0/.omnisharp/1.32.18/omnisharp/Omnisharp.exe.
Other troubleshooting I attempted in this instance though to no avail:
dotnet clean / Deleting bin and obj directories
Updating launch.json to point at the proper /bin/Debug/netcoreapp2.1 build
directory
Wiping my local nuget cache
Restarting Omnisharp
Uninstalling and reinstalling VS Code, as well as bumping back a version from 1.33.1 as the breakage coincided oddly with the March 2019 update
Uninstalling and reinstalling the C# VS Code extension, as well as bumping back a version from 1.19.0 given other users' reports of said version interfering with Intellisense for certain projects*
Adding a global.json file at project root to override default utilization of latest .NET Core SDK (mine was 2.2.105) and run instead using 2.1.302 in concert with the project's version
Wiping/rebuilding the project .sln file
Specs: VS Code 1.33.1, C# Extension 1.19.0, MacOS High Sierra 10.13.6.
*NB: As it turns out, in another .NET Core 2.1 project with the same issues in VS Code as described above, uninstalling Mono alone did not fix things. I also did wind up needing to bump back the C# extension to v. 1.18.0 to recover Intellisense. Weird.
The issue I had was OmniSharp was an older version. I set the flag to update to latest version in Settings.json file. This ensures the extension is always the latest version.
"omnisharp.path": "latest"
And restarted VS code. That fixed it for me.
Simply reinstall the extension and restart the VSCode/PC.
I use Task Manager and kill the Visual Studio Code process, then restart Visual Studio Code, the intellisense shows and fixed.
I've had some good experiences in C# with this extension so far:
https://marketplace.visualstudio.com/items?itemName=jchannon.csharpextensions
This extension traverses up the folder tree to find the project.json or *.csproj and uses that as the parent folder to determine namespaces.
Try "Install Extension" from command Pallete - probably if C# intellisense is not there:
https://code.visualstudio.com/docs/customization/colorizer
if intellisense in not working for react js or javascript or node js this solution will help for windows
uninistall type script by typing npm uninstall -g typescript
install specific version of type script that is 3.3 by typing npm install -g typescript#3.3
add the typescript location in vscode by navigating to file > Preferences > settings > here search for edit in setting.json then add this path "typescript.tsdk": "/Users/yourusename/AppData/Roaming/npm/node_modules/typescript/lib"
settings.json should look someting like this
{
"editor.suggestSelection": "first",
"vsintellicode.modify.editor.suggestSelection":"automaticallyOverrodeDefaultValue",
"typescript.tsdk": "/Users/yourusername/AppData/Roaming/npm/node_modules/typescript/lib"
}
I was able to fix this by changing the Api Compatibility Level from .Net Standard 2.0 to .NT 4.x. You can find this setting on Project Settings / Player.
After that, intellisense started working again.
This is because of C# extension issue.
Reinstall the extension will work.
https://code.visualstudio.com/docs/editor/intellisense
https://marketplace.visualstudio.com/items?itemName=ms-dotnettools.csharp
I fixed this with a multiple project solution in .net5 / .net core 3.1 by
opening each project (not the sln folder) in VSCODE. This then prompts to add the resources/ .CSX? files to the project; enabling intellisense, per project. Finally close that window and reopen the solution folder and all works as expected.
See image
Add VSCode assets
Downgrading to 1.23.9 of C# for Visual Studio Code (powered by OmniSharp).
https://i.stack.imgur.com/VrdJl.png
After trying several things I looked at the OmniSharp logs only to realize that because I had two different sln files in my workspace. It had picked up the “other” one and thus wasn’t working. I deleted it, reopened vs code, and all is well again.
For me I had been working without internet for a long time. It had previously been working but then stopped. I closed+reopened VSCode with a stable wifi connection and the Output tab in VSCode popped up, displaying the the extensions were re-installing. After that it worked!
in my case , the extension wasn't enabled
I just had this happen (this being no code completion suggestions appearing). What resolved it for me was changing the VSCode Editor package in Unity to a previous version and then back to the current version.
For me, this was going from 1.2.0 to 1.1.3 and then back to 1.2.0. I believe removing and reinstalling 1.2.0 would have accomplished the same.
Window > Package Manager > Visual Studio Code Editor
I know this is probably the most obvious answer. But I had enough dealing with VS Code ridiculous bugs. You should be focusing on code, not the buggy IDE. Their documentation doesn't make it easy either to debug.
Steps for complete uninstallation:
Save your personalization files such as keybindings.json,
Just put it on GitHub or something so whenever you need have trouble with VS Code you simply just need to go to GitHub and copy-paste it.
Uninstall VS Code completely
When you uninstalled VS Code, it doesn't erase your extension files and some old settings. This is the cause of the re-installation ended up the same. Horrible move VS Code. For the list of the files that you must delete, you can check out this answer.
Go to their website and install the new one.
I hope this helps some people who are already had enough with the VS Code ridiculous bug.
In my case, the issue was not with VS Code settings. The error was due to a corrupted TEMP path configured in my PC's registry user profile environment settings.
I got this error from Help --> Toggle Developer Tools --> Console
The error was flagged in the console when I opened a new typescript file.
Unable to write file c:\Users\XXX\AppData\Local\Temp;C:\wamp64\bin\php\php5.6.25;C:\vufind-3.1.2\install.php\09cf49d8-af5b-42e9-8194-43f5b566be0f'
Obviously this path was corrupted. After updating the environment variables in registry settings, the VS code IntelliSense started working. Checking the console is a good start to find the root cause of this issue.
Earlier intellisense was working for Angular in VS-Code but for some reason (which I don't know) intellisense stopped working. I had extensions installed i.e. Angular Essentials and Angular Language Service etc. that were responsible for this intellisense and all that.
What I did?
I disabled the extensions, restarted VS Code and enabled them. It was all working fine as before.
If everything in VSCode is working ( No errors in output console, language server is working etc.) and built-in extensions are enabled. Still, if your IntelliSense is not working for normal .js files make sure variables are defined with a type identifier such as var d = new Date() or let d = new Date(). In my case, IntelliSense was not working for d = new Date() (No autocomplete for Date object 'd' APIs in this way) but started working fine when I specified a type before my variable names.
Download and install "Tool for Visual Studio 2019" as the C# extension under hood use the build tools: https://visualstudio.microsoft.com/downloads/
In my case, I had an extension installed (Explorer Exclude) to help me focus and hide certain files that I don't regularly work with within the Explorer.
I so happened to have disabled viewing *.sln, *.csproj and *.vsconfig files and folders, which apparently prevents VSCode from even knowing the file is there in the first place. Disabling these specific rules solved the problem instantly.
Took me ages to figure out... The more you know.
I solved it by uninstalling all SDK's (not sure if this is needed)
and installed 4.7.1 developer pack
win 10, vscode 1.63.2, unity 2020.3.25f1
I fixed this by installing .NET Framework 4.7.1 Developer Pack:
https://dotnet.microsoft.com/en-us/download/dotnet-framework/net471
I am using Visual Studio Code and I have already loaded C# OMNISharp plugin to my system and it works all fine in my existing project/solutions.
However, I just created a new solution and a new project in Visual Studio code and it sounds like for this particular solution, the Intellisense or any other Omnisharp features are just not working. I have tried following things:
Restarting Visual Studio Code
Disabling and enabling my OmniSharp Plug-in
Also, one thing that I noticed is that when a solution is created in Visual studio, it has a lot of code which looks like following:
Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{AEA16303-6991-4FF1-A3A9-72D892D7968C}"
EndProject
Basically, these are all project references. However, when a solution is created by Visual Studio Code then there is not any section like that. This solution runs and compiles fine, just that it looks fundamentally different than how a Visual Studio solution looks like.
However, nothing seems to be working. Is there anything that I can try to make it work? Any ideas ?
It's caused by adding *.sln and *.csproj to your "files.exclude" setting.
Try this:
Code -> Preferences -> Settings -> "omnisharp.useMono": true/false
Remove from setting file.
Or, Open your project with MonoDevelop or Visual Studio 2015/2017 first, then reopen VS-Code.
Edit 1: Try setting "omnisharp.useGlobalMono": never and then restarting the omnisharp server.
Credit: The_Wolf and kao peter
How did you created the project?
For the Intellisense to work properly the project needs to have a specific structure.
Assuming you have the .net core sdk for mac and the omnisharp extension installed:
Try the following:
Open your integrated terminal (View => Integrated terminal)
Create some new directory to host a test project say "testproj" e.g => mkdir testproj
use the dotnet cli to initialize the project => dotnet new console
See if you got intellisense.
Also i'd recommend watching the .net core on Mac introduction video.
In VS Code v1.43.2 adding following line to settings worked for me:
"omnisharp.useGlobalMono": "never"
The setting's value "never" had to be double-quoted otherwise it would be flagged in red. Even with the quotes, it remained highlighted in yellow. Not sure why, as all other options/values in there are blue. I presume this indicates some sort of warning, but it works.
(As an aside, I would love to understand what a "Globally installed mono" is. However my only interest here was getting IntelliSense working, so re: omnisharp I'm pleading 'newb'.)
This worked for me
"omnisharp.useGlobalMono": "never"
Were your new solution and projects created in a "OneDrive" folder in Windows 10? In latest Windows 10 release, the C# plugin can't start up when a project resides in a OneDrive folder with "File On-Demand" feature on. Please take a look at this issue on Github
I my case, the problem came from the resource folder of my project.
I had added a visual studio .sln file in the ressources to be used as a template but I somehow "variabilized" it with custom tags. OmniSharp tried to parse it and obviously failed, but no error poped up in VSCode, it was only visible in OmniSharp output.
The solution was to rename the template from .sln to .txt to prevent OmniSharp from loading it.
In my case, after installing C# extension, I had to click the setting icon on the extension and then click "Add to workspace recormendations"
I had this problem in 2022 and nothing mentioned above worked for me.
For me the problem was caused by VS Code and C# plugin being updated (in my case c# plugin to v1.25.0+) because in this version they made this:
.NET Framework builds of OmniSharp no longer ship with Mono or the MSBuild tooling (See announcement omnisharp-roslyn#2339). To ensure that the C# > > extension remains usable out of the box for .NET SDK projects, we have > changed the default value of omnisharp.useModernNet to true.
If you still need Unity or .NET Framework support, you can set > omnisharp.useModernNet to false in your VS Code settings and restart OmniSharp.
So entier problem was in omnisharp.useModernNet being set to true by default which renders entire plugin unfunctional but doing what they said and setting
omnisharp.useModernNet to false manually in .vscode > settings.json file solved this problem for me!
For more info, you can also read the entire official VS Code C# Plugin announcement under plugins Details section in VS Code or on this webpage as well!
I have a solution in VS 2012,
I try to change the startup project to specific project but the vs crashing immediately (with the other projects - no problem)
with the familiar message "Visual Studion Stop Working.."
I try also to define the startup project manualy in the .suo file
(See details in Why is "Set as Startup" option stored in the suo file and not the sln file?)
But when i reopen the VS, it crashes during the assemblies loading.
Any idea what can be the cause?
Edit:
Additional Details:
Its solution contains also WCF project, run in front of local IIS, This project run perfectly, with the same code, in other team computers.
As result of the facts, It seems an environment problem, IIS setting, Permissions and etc.
Note that i already reset VS setting, and also repair the installation and the problem not resolved.
Maybe someone knows what the logical action of 'Set as startup project', what the VS perform during the action except for the start point definition? i think that the root of the problem hides there...
I had this problem too, but on VS 2015. You should logoff from your MS account from VS, set your project as startup and then login back if you want ...
It is hard to guess what the problem could be, but because it works on other team members' machine, it might have something to do with your Visual Studio state.
Try clearing or moving out all files from:
C:\Users\<Username>\AppData\Local\Microsoft\VisualStudio (if starting as admin)
C:\Users\<Username>\AppData\Roaming\Microsoft\VisualStudio (if not starting as admin)
You might need to restart your machine if the files are in use before you can delete/move them. These folders contain some VS settings, cached files and logs.
In addition to what AVS said, you can try deleting your Visual Studio .suo file.
I have started a new console project in VS2015. I only have this code :
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using SautinSoft;
namespace PdfParser
{
class Program
{
static void Main(string[] args)
{
string path = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
SautinSoft.PdfFocus f = new PdfFocus();
f.OpenPdf(#"path:\abc.pdf");
if (f.PageCount > 0)
f.ToExcel(#"path:\abc.xls");
}
}
}
When I try to run, I get this :
Unable to start debugging. The startup project could not be launched.
Verify debug settings for the startup project.
How can I fix this? Thanks.
After upgrading MSVC2015 to Update3, I had the same problem: instead of std::map in the Watch window display as a horrible std::_Tree<std::_Tmap_traits... etc., some plugins started to throw exceptions, some projects was not able to run in debug mode.
All was solved by deleting CurrentSettings.vssettings. It is usually located at Documents\Visual Studio 2015\Settings If not, go to `Tools -> Options -> Environment -> Import and Export Settings ' to find the location of this file.
Had this on a brand new scaffolded ASP.NET Core 1.0 web application.
Solved with restart of Visual Studio.
I was also stuck with this. I removed both bin & obj folders, did a rebuild, and then it launched.
A very meaningless error....
I had this problem when I tried to start (without) Debugging my Asp.Net MVC project
are you running Visual studio as Administrator
so just restart visual studio As Administrator
Additionally to "Unable to start debugging"
I also had errors "The operation could not be completed: Unspecified error" when I tried to rebuild.
Thanks to Visual Studio popup: "the operation could not be completed"
it was enough to close Visual Studio 2015 and then open again.
Make sure you're launching Visual Studio as Administrator.
Right click on the Visual Studio 2015 Shortcut
Select the Shortcut tab
Click on Advanced
Check the box to "Run as administrator" at all times(see below)
This has resolved the issue for me with the exact error message in question.
It is not ideal to run the VS in administrator mode at all times. Make sure you un-check the box once your issue has been resolved.
There is no need to delete everything in my case, I just opened the
"CurrentSettings.vssettings"
file and commented this property
<PropertyValue name="DefaultBehaviorForStartupProjects">1</PropertyValue>
and everything fixed.
Sample
Just delete the .vs hidden folder. This folder resides at the same location where the sln file is. Deleting this folder also refreshes intellisense cache and would fix any issues with that. Hope this helps.
VS 2019, two Core 3.1 projects (an MVC and an API), brand new projects created, no other changes to the solution or projects.
I kept getting the referenced error when trying to start both projects within the IDE, despite having checked all the things already mentioned in this SO.
However, I finally realized, I forgot to specify the "Action" after switching the solution to "Multiple startup projects" (they were both still set to "None"). Right-click solution in "Solution Explorer", choose "Properties" (at very bottom).
Such a ridiculously simple thing. Hope it helps someone else.
"Broken"
Working
I just had the same problem and solved it by deleting the .vs directory in the project directory.
Delete all relevant /obj and /bin folders. Run again.
Close the Visual Studio and re-open it again.
Just restart your visual studio and run as admin.
I had this with a Xamarin.iOS project in my Xamarin.Forms solution. I tried every suggestion here, without success.
The source of the error was a misconfigured .csproj of the project. I never edited it myself and not even touched the project properties. I use Visual Studio 2017 RC.
I came across the solution when I compared the project file with previous versions on Source Control.
Solution: Compare the project file with a previous version and try to granually revert changes until you eliminated the problem and know what the cause was.
The solution for me was to delete all *.user files that are normally generated for both solution and project files
I found this problem too. But after restart the Visual Studio Community 2015 as an administrator I found new problem :
And then I try to open another solution, close the another solution, and open the solution which the problem occur, then the problem solved.
Had the Same Issue with the existing application, I deleted the vs settings but still the issue remained,
Finally i just restarted the VS and it worked fine.
I think sometimes when we load the project some library doesn't get loaded with the solution so the best option before doing anything is simply restarting the VS.
After adding a project reference 'MyProjectReference' to my app, then removing it, I was also getting the same error :
Unable to start debugging . The startup project could not be launched.
Verify debug settings for the startup project.
Deleting configuration, running as admin, restarting VS, rebooting machine all had no effect.
After running my web app without debugging (Right-Click Project -> View In Browser (Google Chrome) I got a much more useful error:
Could not load file or assembly 'MyProjectReference' or one of its
dependencies. An attempt was made to load a program with an incorrect
format.
My Solution was then to re-add back to the solution, then remove it again. After that rebuild and debug worked.
How I fixed my issue, I closed project that had that error , created new project build new project then opened the project that had an issue and build it. That worked for me.
Make sure you close all instances of Visual Studio and then restart as Administrator. In my case I had multiple instances of Visual Studio open and I had to close them all and then restart Visual Studio as admin in order to get things working.
I had visual studio 2015 with an ASP.net MVC5 arcitectured with DDD (Domain Driven Design). The problem was the same since I just opened visual studio normally.
The problem was solved when I closed all instance visual studio and restarted as an adminstrator.
I also faced to this issue in VS 2015 , but finally I resolved it by following bellow steps
In VS go to : Tools -> Options - > Projects and Solutions -> Build and Run
Select "Always Build" in "On Run when project are out of date"
This issue happened to me with the Latest VS2019.
I've tried everything here, but unfortunately without any result.
Finally, I've restarted the IIS server, also manually Recycled the "Default Application Pool".
After debugging issue fixed.
For me solution was to run testapp.csproj instead of testapp.sln. This can be selected from drop down next to green play button.
Simply updated visual studio which then prompted PC restart. This is what fixed the problem for me.
Note: I tried some of the above / below but to no avail.
I got this problem solved by clearing MEF component cache.
Use this VS Extension to clear cache very easily.!!
I stop debugging and exit the projects from IIS Express then clean and build the project and my error is gone.
I get this running as non-Adminsitrator in Visual Studio 2019 16.2.5, with two .NET Core projects.
The solution I found is to set at least one of the projects as "Start" (in Solution's Property Page). If both are set to "Start without Debugging" it fails. This happens even if I want to start the entire project without any debugging (Ctrl+F5).
Bug. Still unaddressed by Microsoft and their bug page issue report it is closed as unreproducible.
#Flowerking's commend did it for me.
Right click on you project and select "Set as StartUp Project".
I had this problem developing a react native app for windows in Visual Studio 2019. I started the debugger then stopped it in the terminal by using ctrl-C. I was not able to restart the debugger and the "start debugging" and "start without debugging" options were disabled in the debug dropdown. Restarting Visual Studio, etc, and some of the things described above did not work. Through hunting and testing, I noticed that if I switched views in the Solution Explorer to the MyProject.sln instead of the fileview, the debugging was enabled again. I'm not sure why, but it appears I need to be in the sln view to start the debugger.
I am working on a WPF, C# 3.0 project, and I get this error:
Error 1 Metadata file
'WORK=- \Tools\VersionManagementSystem\BusinessLogicLayer\bin\Debug
\BusinessLogicLayer.dll' could not be found C:\-=WORK=- \Tools
\VersionManagementSystem\VersionManagementSystem\CSC VersionManagementSystem
This is how I reference my usercontrols:
xmlns:vms="clr-namespace:VersionManagementSystem"
<vms:SignOffProjectListing Margin="5"/>
It happens after every failed build. The only way I can get the solution to compile is to comment out all my user controls and re-build the project, and then I uncomment the usercontrols and everything is fine.
I have checked build orders and dependencies configurations.
As you can see, it seems to have truncated the DLL file's absolute path... I have read that there is a bug with the length. Is this a possible problem?
It's very annoying and having to comment, build, and uncomment, the build is becoming extremely tiresome.
I just had the same problem. Visual Studio isn't building the project that's being referenced.
Written Instructions:
Right click on the solution and click Properties.
Click Configuration on the left.
Make sure the check box under "Build" for the project it can't find is checked. If it is already checked, uncheck, hit apply and check the boxes again.
(Optional) You had to do it for both Release and Debug modes on the solution properties.
Screen capture Instructions:
They say a picture is worth a thousand words. Click on the GIF to zoom in, and hopefully it will be easy to follow:
This can still happen in newer versions of Visual Studio (I just had it happen on Visual Studio 2013):
Another thing to try is to close Visual Studio and delete the .suo file that is next to the .sln file. (It will be re-generated the next time you Save all (or exit Visual Studio)).
I've had this problem when adding new projects to the solution on another machine and then pulling the revisions in, but the .suo file can be corrupted in other cases as well and lead to very strange Visual Studio behaviour, so deleting it is one of the things I always try.
Note that deleting the .suo file will reset the startup project(s) of the solution.
More on the .suo file is here.
The suggested answer did not work for me. The error is a decoy for another problem.
I found out that I was targeting a slightly different version of .NET and this was flagged as a warning by the compiler, but it was causing building to fail.
This should have been flagged as an error and not a warning.
Well, my answer is not just the summary of all the solutions, but it offers more than that.
Section (1):
In general solutions:
I had four errors of this kind (‘metadata file could not be found’) along with one error saying 'Source File Could Not Be Opened (‘Unspecified error ‘)'.
I tried to get rid of ‘metadata file could not be found’ error. For that, I read many posts, blogs, etc. and found these solutions may be effective (summarizing them over here):
Restart Visual Studio and try building again.
Go to 'Solution Explorer'. Right click on Solution. Go to Properties. Go to 'Configuration Manager'. Check if the checkboxes under 'Build' are checked or not. If any or all of them are unchecked, then check them and try building again.
If the above solution(s) do not work, then follow sequence mentioned in step 2 above, and even if all the checkboxes are checked, uncheck them, check again and try to build again.
Build Order and Project Dependencies:
Go to 'Solution Explorer'. Right click on Solution. Go to 'Project Dependencies...'. You will see two tabs: 'Dependencies' and 'Build Order'. This build order is the one in which solution builds. Check the project dependencies and the build order to verify if some project (say 'project1') which is dependent on other (say 'project2') is trying to build before that one (project2). This might be the cause for the error.
Check the path of the missing .dll:
Check the path of the missing .dll. If the path contains space or any other invalid path character, remove it and try building again.
If this is the cause, then adjust the build order.
Section (2):
My particular case:
I tried all the steps above with various permutations and combinations with restarting Visual Studio a few times. But, it did not help me.
So, I decided to get rid of other error I was coming across ('Source File Could Not Be Opened (‘Unspecified error ‘)').
I came across a blog post: TFS Error–Source File Could Not Be Opened (‘Unspecified error ‘)
I tried the steps mentioned in that blog post, and I got rid of the error 'Source File Could Not Be Opened (‘Unspecified error ‘)' and surprisingly I got rid of other errors (‘metadata file could not be found’) as well.
Section (3):
Moral of the story:
Try all solutions as mentioned in section (1) above (and any other solutions) for getting rid of the error. If nothing works out, as per the blog mentioned in section (2) above, delete the entries of all source files which are no longer present in the source control and the file system from your .csproj file.
In my case it was caused by a .NET Framework version mismatch.
One project was 3.5 and the other referencing project 4.6.1.
Visual Studio 2019 this worked for me:
Close Visual Studio
Delete the hidden .vs folder
Reopen Visual Studio and rebuild the solution.
Closing and reopening Visual Studio 2013 worked for me!
Well, nothing in the previous answers worked for me, so it got me thinking about why am I clicking and hoping when as developers we should really try to understand what is going on here.
It seemed obvious to me that this incorrect meta data file reference must be held somewhere.
A quick search of the .csproj file showed the guilty lines. I had a section called <itemGroup> that seemed to be hanging onto the old incorrect filepath.
<ItemGroup>
<ProjectReference Include="..\..\..\MySiteOld\MySite.Entities\MySite.Entities.csproj">
<Project>{5b0a347e-cd9a-4746-a3b6-99d6d010a6c2}</Project>
<Name>Beeyp.Entities</Name>
</ProjectReference>
...
So a simple fix really:
Backup your .csproj file.
Find the incorrect paths in the .csproj file and rename appropriately.
Please make sure you backup your old .csproj before you fiddle.
In my case, I have my installed directory in mistaken ways.
If your solution path is something like "My Project%2c Very Popular%2c Unit Testing%2c Software and Hardware.zip", it cannot resolve the metadata file, perhaps we should prevent some invalid words like %2c.
When a repository is cloned from certain sites, the directory name is URL encoded. Which would convert space characters in directory names to %20, forward slashes to %2f, underscores to %5f, etc. Although, I'm not sure why the % symbol is breaking things.
Renaming the path into a normal name resolved my issue.
I also met this problem. Firstly you have to manually build you DLL project, by right-click, Build. Then it will work.
In my case, the problem was caused by a simple build error,
error CS0067: The event 'XYZ' is never used
that, for any reason, did not show up in the error window.
Because of that, the Visual Studio build system seemed to miss the error and tried to build dependent projects, which in turn failed with the annoying metadata message.
The recommendation is -as stupid as it may sound-:
First look at your Output Window!
It took me half an hour before this idea hit me...
I got the same error "Metadata file '.dll' could not be found", and I tried several things described above, but the reason for the error was that I was referencing third-party DLL file which was targeting a .NET version higher that my project target .NET version. So the solution was to change the target framework of my project.
I added a new project to my solution and started getting this.
The reason? The project I brought in was targeting a different .NET framework (4.6 and my other two were 4.5.2).
For me, it was trying to find a DLL in a path that used to contain the Project, but we'd moved it to a new directory. The Solution had the correct path to the Project, but Visual Studio somehow kept looking in the old location.
Solution: Rename each problem Project - just add a character or whatever - then rename it back to its original name.
This must reset some global cache of some kind in Visual Studio, because this clears both this issue up and several like it, while things like Clean do not.
It looks like such kind of errors related to the fact that Visual Studio doesn't provide correct information about an error. The developer doesn't even understand the reason for the failed build. It can be a syntax error or something else. In common, to solve such problems you should find the root of the problem (for example, look at the build log).
In my case the problem was in fact that the Error List window didn't show any errors. But really there were syntax errors; I found these errors in the Output window, and after fixing them, the problem was solved.
For me it occurred when I included a new project to a solution.
Visual Studio automatically selects .NET framework 4.5.
I changed to version .NET 4.5.2 like the other libraries, and it worked.
If you have a space in your solution name, this will also cause the issue. Removing the space from your solution name, so path doesn't contain %20 will solve this.
Coming back to this a few years later, this problem is more than likely related to the Windows maximum path limit:
Naming Files, Paths, and Namespaces, Maximum Path Length Limitation
For me the following steps worked:
Find the project that is not building
Remove/add references to projects within the solution.
I was pulling my hair out with this problem also, but after trying the previous answers the only thing that worked for me was to open each project in my solution 1 by 1 and build them individually.
Then I closed Visual Studio 2013, reopened my solution and it compiled fine.
It's strange, because if I clicked each project in my Solution Explorer and tried to build them that way, they all failed. I had to open them alone in their own solutions.
In my case the issue was that I'd manually deleted a non-compilation file which was marked as "missing". Once I deleted the reference to the now-missing file and recompiled - all was well.
My instance of the problem was caused by a common project that had a duplicate class name in it (under a different filename). It is strange that Visual Studio could not detect that and instead just blew up the build process.
I got this problem in Visual Studio 2012 in a solution that had many projects. Rebuilding each project in the solution manually in the same order as the Project Build Order (right-click and rebuild in Solution Explorer) fixed it for me.
Eventually I got to one that gave me a compile error. I fixed the error, and the solution would build correctly after that.
I too had the same error. It hides as in the below path.
The path which I referred to for the DLL file is like "D:\Assemblies Folder\Assembly1.dll".
But the original path in which the assembly referred was "D:\Assemblies%20Folder\Assembly1.dll".
Due to this path name variation, the assembly could not be retrieved from its original path and hence throws the "Metadata not found" error.
The solution is in Stack Overflow question How do I replace all the spaces with %20 in C#?.
Most of the methods explained here did not solved the problem for me.
Finally, I fixed the problem by applying the following steps:
1. Close Visual Studio.
2. Delete all the contents in the bin folders of each project.
3. Open solution and rebuild.
I hit and solved this problem today on VS2022 in a solution with a Blazor project.
The underlying problem is that I had introduced a routine C# compilation error
in C# code declared in a .razor file. VS2022 was dropping the display of the error from the Build Error List tab. I found the C# error by scanning the build output in the Output console log tab where my C# error was described as expected.
p.s. In case you are wondering, I had a Unit Test project referencing my Blazor web project. The project DLL reference from the Unit Test project to the Blazor app was complaining about the missing Blazor DLL.
Based on the error message I don't believe the file path is being truncated. It looks to just be incorrect. If I'm reading the message correctly it appears to be looking for the DLL file at ...
WORK=-\Tools\VersionManagementSystem\BusinessLogicLayer\bin\Debug\BusinessLogicLayer.dll
This is not a valid path. Is it possible that you have a macro definition in the build process set to an invalid value?
I'd faced the same problem. In my case I'd referenced to a class library project with higher .Net version than my project and VS failed to build the project and raised the same error you posted.
I simply set .Net version of my class library project(the one that had broken the build) identical to the .Net version of referenced project and problem solved.
Just pointing out the blatantly obvious: if you don't have "Show output window when build starts" enabled, make sure you're noticing if your build is failing (small "build failed" error in lower left)!!!!
I had this error when I was trying to publish a web application. Turned out that one of a class properties was wrapped into
#if DEBUG
public int SomeProperty { get; set; }
#endif
but the property usage was not. The publishing was done in Release configuration without the DEBUG symbol, obviously.