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I'm running my .NET 4.0 (C#) project in debug mode after I start VS2013. It runs just fine.
The second time I start it from VS, I get the Dialog box that says "Error while trying to run project: Unable to start program C:\path\to\file.exe"
The process is still alive in the Taskmanager when I dismiss the dialog box.
From Windows Explorer, I can run the program just fine. And after closing it, the process is gone too from the Task Manager.
A rebuild doesn't help.
Is this a common problem with a known solution?
I had an issue similar to this and I had to clear the component cache instruction can be found Here.
Hope this helps.
For my case, it cause by Platform target, you could force choose it to x86 or x64 which your project is:
Each Project's Properties > Build > Platform target
As I pointed out also here, the only solution that worked for me was to disable the ConEmu integration:
ConEmu → Settings → Integration → Default term → disable Force ConEmu as default terminal for console applications
Some users reported that it was enough for them to disable the Aggressive mode in that same settings tab; that wasn't the case for me though.
The topic is old, but this might help someone else.
So in my case I made a file in Visual Studio with .cp extension (accidentally deleted the last 'p') this made visual studio just "include" the the file and not mark it as a compilation unit, thus not compiling it, I looked the *.vcxproj file in a text editor and found out about this, so if you open the project file in a notepad or something just find your file at the bottom usually and change from <Item .../> to <ClCompile .../>
I was getting similar errors. I just had to restart visual studio. Sometime couple times a day.
I had a similar error and resolved it by cleaning the solution. Right-click the solution name in Solution Explorer and choose Clean Solution.
I found a solution here:
Please check "Use Managed Compatibility Mode" under Tools|->Options->Debugging->General.
I'm Brazilian, I don't speak English very well. I did this translation on google translator.
I know the topic is old, but it can still help someone.
I had this same problem in the following situation, I have a dual boot computer (linux debian 11 and windows 10). Inside debian, on my NTFS D disk, I created a folder to perform programming tests. After accessing that same folder with windows, I created a new project in visual studio inside that same folder that I had created in linux. The creation of the project went without problems, however when I tried to run the project (F5), I received the same error from this topic. I tried all the solutions I found on the internet, and nothing worked. I gave all permissions to my admin user and it still didn't work. Then I realized that even going straight to the folder where the application's executable was and clicking directly on it, I still received the access denied error message. So, I took the project out of the folder I had created in linux, and it worked. So, what I could conclude, is that because the folder where my project was was created in linux, for some reason, my windows didn't trust this folder, so it didn't allow running executables from inside that folder, even this one executable having been created by visual studio from within windows.
Just simply create a folder name as "projects" in c drive and copy paste the newly created project in it. Run the project by doing clean & Build or Rebuild method . It will work
open the folder which contains the solution in visual studio.
again, open your *.sln file by double clicking it inside the solution explore once opened try running the solution or rebuild the solution. once rebuild gets completed, it will open without error from next time.
My way of solving the error : error while trying to load project : Unable to start program and c:\Path\to\file.exe was simply by
First restart Visual Studio
Click the build icon
Select the rebuild option
Run the Program or Debug the Program
This was a weird one. Going to put what happened to me here because it might happen to someone else. Everything was fine with the app until suddenly after some fairly insignificant code changes I suddenly started getting this error. Visual Studio was compiling the executable just fine. But, the moment I tried to run it (either from Visual Studio or directly) the executable file would be automatically deleted right out of the Debug folder. Super odd--never seen anything like it. I began to get suspicious that perhaps an anti-virus or the OS was somehow identifying a checksum or some signature in the executable as "dangerous". Or perhaps some obscure compilation bug was corrupting the executable. So on a hunch I made another innocuous change (added a couple of lines of code to color code some text in a rich text box) and the problem went away.
I have a Xamarin project, which is based on MvvmCross. The project is for both iOS and Android. I opened this project in Visual Studio 15. I got some errors, which I solved in no time. There are some errors, which are stuck and I couldn't solve them even after searching on Google and on Stackoverflow. I have tried each and every method found on Stackoverflow, but still all remaining errors are there.
This project is using 3rd party libraries like RestSharp and BoxApi.V2 (few more)
I am posting my error log below.
Severity Code Description Project File Line Suppression State
Error The "ResolveLibraryProjectImports" task failed unexpectedly.
System.IO.FileNotFoundException: Could not load assembly 'RestSharp(Android), Version=0.0.0.0, Culture=neutral, PublicKeyToken='. Perhaps it doesn't exist in the Mono for Android profile?
File name: 'RestSharp(Android).dll'
at Java.Interop.Tools.Cecil.DirectoryAssemblyResolver.Resolve(AssemblyNameReference reference, ReaderParameters parameters)
at Java.Interop.Tools.Cecil.DirectoryAssemblyResolver.Resolve(String fullName, ReaderParameters parameters)
at Java.Interop.Tools.Cecil.DirectoryAssemblyResolver.Resolve(String fullName)
at Java.Interop.Tools.Cecil.DirectoryAssemblyResolver.GetAssembly(String fileName)
at Xamarin.Android.Tasks.ResolveLibraryProjectImports.Extract(DirectoryAssemblyResolver res, ICollection`1 jars, ICollection`1 resolvedResourceDirectories, ICollection`1 resolvedAssetDirectories, ICollection`1 resolvedEnvironments)
at Xamarin.Android.Tasks.ResolveLibraryProjectImports.Execute()
at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext() BoxApi.V2 (Android)
This error is repeating for all projects included in this solution. So I am getting this error multiple times.
I also want to add that the project was previously built on MAC and I am using windows, does this make some compatibility or cross OS issue?
I have checked all assembly references and all are working fine.
I've literally just had this with a brand new Xamarin.Forms application in Visual Studio 2017.
The root cause appears to be that I let VS2017 create the project in it's default location 'C:\Users\Dave\Documents\Visual Studio 2017\Projects' and this has resulted in one of more files now having a path which it too long.
I moved the solution to the root of my D drive and it builds without any problem.
Your issue is most likely linked to this post on the Xamarin forums, and this bugzilla entry. Without a reproducible sample, all I can advise you try is:
Updating Xamarin for Visual Studio, Xamarin.Android, and Xamarin.iOS
to the latest stable versions
Cleaning and rebuilding
Deleting all of the bin and obj folders from your project directories
Restarting Visual Studio/your PC
Failing all of that, there's not likely to be anyone who can help you without a reproducible sample and potentially your Xamarin logs.
edit your android project file (csproj) like below
this issue topic may guide https://github.com/xamarin/AndroidSupportComponents/issues/51
Had same problem. Here is my solution
Restart Visual Studio
Open the Project
Clean the solution
Rebuild the solution
Close solution
Reopen the project
I'm working with XAML (.xaml) and code-behind file (.xaml.cs). My issue was that I had the same page name, but under different namespaces. The XAML and the code behind file didn't match together. So finally it was an issue with my XAML, because of course it couldn't find the view element.
Well for me the problem was in my xaml file...
Somehow while setting the Layout bounds i used '.' as a separator instead of ','
e.g
AbsoluteLayout.LayoutBounds="0.5.0.3,1,0.3" should have been AbsoluteLayout.LayoutBounds="0.5,0.3,1,0.3"
Hence changing the '.' to ',' solved the problem
This happened to me when I accidentally installed nuget packages in a class library that was included in the solution. I just had to uninstall the packages from the class library project.
In my case, this issue came with another related to my xaml.
I had to solved the second in order this error dissapear. I clean up the class with a new default content and then clean all projects and solution. By last, close visual studio, open it , run the project and It works know .-.
This is still a fresh problem, after all attempts i wanted to try to shift the code to a shorter path - however that is lot of work as svn management will get complicated, so i wanted to first verify if path is really an issue, one way to do this was to check where the android SDKs are stored. I am on mac and the investigation revealed that SDKs path was longer than my project path. Plus i tried with a fresh project, and that was compiling correctly.
So i dropped the idea of shifting. Instead i used svn and compared what has changed since last correct build.
The comparison revealed that the project file of droid was somehow referring to the project file of iOS, it seems like some bug of Visual Studio. So i reverted the changes and than all got back to normal.
i get the same error and i usually solve this by closing all other opened xamarin solutions and there is one more way i had solved this issue -> go to taskmanager and find MSBUILD Service and end that service -> clean your solution -> Rebuild
We have encountered this too, it appears to be some type of race condition when building multiple projects and a very deep/complex dependency tree (our example has over 100 projects).
The only way we've been able to resolve this (beyond continually rebuilding) is to disable Visual Studio 2017's Parallel Build Abilities (Tools->Options->Projects and Solutions->Build and Run->"1" Maximum number of parallel project builds).
The problem appears to be in ResolveLibraryProjectImports.cs (https://github.com/xamarin/xamarin-android/blob/93ddf96f86710ad848d5189858567dd7fe964579/src/Xamarin.Android.Build.Tasks/Tasks/ResolveLibraryProjectImports.cs) there is most likely a race condition with their logic to shorten up the file names.
There are zero tests around this which means there is most likely some dodgy code.
I am going to attempt to dig more and get an issue opened up on GitHub but finding a reliable repo is probably going to be very difficult.
This worked for me:
Clean solution
Build one project at a time starting at the top - NOT rebuild solution - just one project at a time
Try deleting the contents of Obj and bin folder as well
When done delete the project from the emulator or device before you run it again
Hope this helps.
Still have issues ? Check your namespaces and your xaml code. Sometimes when you copy/paste some files, it can be the problem.
Not sure if it will help anyone of you. For my case, I comment the erroneous class (eg. those with missing references), and it will start to pick up everything and build again.
In my case, I just forgot to delete the clicked event in XAML that doesn't exist in my code behind(cs file). After that, I just clean and rebuild.
I think that error was caused by not updated references.
It's probably an issue with your references / reference assemblies?
If you look under each project's references folder in the solution explorer, any references that visual studio cannot find, delete and re-add them (right click reference folder to add).
I have Faced this issue a thousand times its actually a very simple thing when you create a new project visual studio creates it in C:Drive in its default folder all you have to do is move your project out in some other Drive Like D:, E: whatever just make sure to keep it in the root of your Drive i.e. If you move it in D: Then place it like this D/Project/solutionFile
Here is the problem:
System.IO.PathTooLongException: The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters.
Try to move you project to another location like "C:/" , or change the name of the project for something more brief
I encountered the same issue and none of the solutions above worked. After noticing and error on the list regarding Cryptography I knew it had to be related to FIPS being enabled (required by a VPN client)
By disabling FIPS and restarting Visual Studio the issue was resolved.
I had this error as well. In my situation it was accompanied by Xamarin.Forms.Maps not importing into the one of the xaml.g.cs files correctly. I had all the using statements correct. The IDE was showing no errors but it kept telling me that Xamarin.Forms did not have a name space Map. It was generating in MapPage.xaml.g.cs as Xamarin.Forms.Map instead of Xamarin.Forms.Maps.Map and I couldn't force a fix manually. It turned out though that the suggested xmlns:maps for maps was causing the problem. The IDE had told me to use "http://xamarin.com/schemas/2014/forms" but the correct namespace is "clr-namespace:Xamarin.Forms.Maps;assembly=Xamarin.Forms.Maps". After I changed this it was able to build my App1.dll
This was how I got the error. In a StackLayout I put in a Padding property, and I seperated the 4 digits by a space rather than a comma.
To find the bug I had to comment out the XAML controls individually and rebuild to isolate where the error is, and eventually I found the problem line.
So basically this was the error message I got for a syntax error in my XAML code!
In any other language I would expect to be informed what the error is so I can fix it in seconds. But this took me a few hours - although next time I know what to do.
This kind of issue may also come if by mistake you have any syntactical error like in my case: two text cells were present in the ListView -
<ListView x:Name="ProductsView">
<ListView.ItemTemplate>
<DataTemplate>
<TextCell Text="{Binding ProductId}" />
<TextCell Text="{Binding ProductDescription}" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
I went through other posts for this issue and found the same issue occurred due to the presence of syntactical errors, which VS doesn't report directly. So look for this, otherwise, reinstall the compatible version of xamarin.forms -> clean solutions -> rebuild by reopening VS.
I have faced the same problem today. After two days searching, I have found the solution here. The issue is Xamarin.Forms library does not install all its dependent Nuget packages while first creating project by choosing cross-platform Mobile(Xamarin.Forms) project template from Visual Studio 2017. I have to manually install the upgraded dependent nuget packages to build the project successfully. Also have removed and added Xamarin.Forms at the end which resolves the issue.
Also, it is some time creating issues when two instances of Visual Studio 2017 is running, make sure only one instance is only running as I have encountered this issue as well.
xmlns:maps="clr-namespace:Xamarin.Forms.Maps; assembly=Xamarin.Forms.Maps"
The problem was because of the space between the semicolon above and the assembly as stated above. As soon as the gap is closed, it compiles.
Shorteninig the path(folder names) to the solution solved it for me.
For example : the path was :
C:\Users\Username\Downloads\Compressed\ListView-GettingStarted-in-Xamarin-Forms-master\ListView-GettingStarted-in-Xamarin-Forms-master\GettingStarted
and i changed it to :
C:\Users\HelloKali\Downloads\Compressed\3\2\1.
Hello there, Stackoverflow.
Recently, when I've been programming in Visual Studio 2010, I've been getting the problem with VS locking the bin/Debug/(ProjectName).exe file when trying to build and gives me the error below after trying to build the project 10 times:
Unable to copy file "obj\x86\Debug\TileEngine.exe" to "bin\x86\Debug\TileEngine.exe". The process cannot access the file 'bin\x86\Debug\TileEngine.exe' becuase it is being used by another process.
The problem appears when I edit the source and then try to Debug.
I've checked using different programs, and the only program using the file is Visual Studio.
If I wait for about 10 minutes before trying to build, it seems to work properly, but when trying different things, it isn't good needing to wait 10 minutes before trying something.
I've tried different solutions both on this site as well as everywhere I can find on Google.
Some solutions I've found, but haven't worked for me
Solution 1 - Using a pre-build script
In some different questions here on Stackoverflow, I've found one solution being that you go into Project Properties > Build Events and then in the Pre-build event command line add:
if exist "$(TargetPath).locked" del "$(TargetPath).locked"
if not exist "$(TargetPath).locked" move "$(TargetPath)" "$(TargetPath).locked"
This made it possible for me to build the project one more time than I usually could, but when editing the code again, and then building, the same error appeared.
Note: Trying to build a release instead of a debug build seems to break the pre-build script and it exits with the code '1', which seems to make VS unable to build properly. Removing the pre-build script makes it work like "normal" again, still with the same error though.
Solution 2 - Running Visual Studio as Administrator
This is another solution I've found, but havent worked either for me, so I assume that Visual Studio already have all the permissions required and running as Administrator doesn't actually make any difference.
Solution 3 - Changing the AssemblyVersion
In this question, Visual Studio build fails: unable to copy exe-file from obj\debug to bin\debug, I found another solution that included changing the AssemblyVersion, in the Properties\AssemblyInfo.cs file, to "2.0.0.0".
This, however, haven't made any difference whatsoever for me.
Solution 4 - Closing UserControl designers before building
According to some different answers here and there on the Internet, Visual Studio apparently uses the built project executable to render the UserControl designer(?). In my case, this is probably not it, though, since I use XNA mostly and it doesn't use the UserControl designer.
Solution 5 - Cleaning up resources when application quits
This might be a solution that I have failed to implement properly. I'm just thinking though, that if this is the solution, how come I haven't been required to do it before. I assume XNA unloads everything that gets loaded through the Content pipeline, therefore this solution wouldn't' make any real sense.
If there is anyone that is able to spread some light on this issue, it would be really awesome, as it is stopping me from programming anything really, because I don't like waiting for 10 minutes because I've made a 2 second change all the time.
I've run into this problem a few times myself.
Mine might not be from the same cause as yours, but I'll tell you what went wrong with me and how I fixed it, hopefully it'll be helpful to you.
Basically, my program never fully exited properly, even when it appeared to. It would continue to run, and thus continue to lock down the file.
A quick dirty fix I used initially (and a way to prove if this is the case) is:
Open Task Manager (Ctrl-Alt-Del)
Click Processes tab
Look for your program's name (TileEngine.exe)
Note: There will probably be name_vshost.exe (TileEngine_vshost.exe) That's a VisualStudio thing, ignore that, it's not relevant.
If you find it, it means your program hasn't actual exited fully.
If it's there, click on it and press "End Process"
So if it's there, then for some reason, your program didn't shut down, like mine did.
Often, this is from a thread being launched and forgotten, or an Async task that never completes, or something like that.
Make sure in your OnExiting(..) void function that you kill all running threads.
If your program is still running despite best attempts to close all threads and other blockers, you can use the very dirty bad method:
In OnExiting(...) run the code "System.Diagnostics.Process.GetCurrentProcess().Kill();" - this will taskmanager-style forceshutdown the current process... this is only as an emergency I-can't-make-it-work-any-other-way method.
I think I found the solution myself.
In the Project Properties, "Enable the Visual Studio hosting process" wasn't checked. Checking it seems to have fixed the problems, at least for now.
Got reminded of it from mcmonkey4eva's post. So thanks for that =)
And thanks for the other replied I've got. Stackoverflow is awesome!
Have you checked if any files are being blocked by your firewall? When I switched to the full version of Avast I find I have to disable the File System Shield It loves to remove my executable files when I try to run my visual studio projects.
I had problems when upgrading to VS2012 Professional. (SDK, .Net, Visual C++ Redistributable package)
ENSURE ALL OF THESE ARE COMPATIBLE WITH THE CURRENT VERSION OF VS YOU ARE USING
What I did, was I ended up uninstalling EVERYTHING that was associated with both Visual Studio downloads. If you are able to remove and save your project files elsewhere and then bring them back. Go through all your program files to see if there is anything hidden in the wrong folder and check your C drive.
Which meant downloading and reinstalling (fresh):
I think if you clean out your program files, it should be ok. I wouldn't recommend going into your register unless you are very sure of what you are doing. IF you have already made changes to the register then we'll have a look at that and other options (if this doesn't solve your problem).
Try removing the readonly check from your solution by unchecking at the folder level.
I ran into this problem and in my case was due to having bin included in the solution; as soon as I excluded the bin folder from my solution the problem went away.
Nothing helped, not prebuild commands, neither designers closing, but I figured out a way that helped me, just changing from debug to release and vice-versa releases locked files and you can delete them without closing the IDE.
I regularly get this problem if I switch from Debug to Release and then immediately F5 to compile. Crazy as it sounds, waiting for, say, one minute after switching between modes will prevent this.
If it's locked, the only solution is to close Visual Studio and re-open.
I solved this problem organizing my resources on solution. I noticed this error when I put some images on my application at the same solution folder.
So,
I'd removed all images and resources from app, save without it.
Moved the images to outside Solution folder.
Open the solution and add this images again, using "Import" button at controls.
If you will try this, remember to do with Application Icon, on Project Settings.
Now, everything is working fine for me.
I hope it helps.
You need to disable Windows Indexer as it locks up the file
Follow this Guide how to disable
In my case the problem seem to be caused by the remote debugger. It starts on local machine when you compile with "x64" option. Try to change the project setting (properties/buid) until you reach the final version.
Change Build Platform target from x86 to Any CPU.
I am new to WPF and .net. I have a WPF app which someone else had written earlier and AFAI remember it was working just fine some time back. But today i see this mysterious error when trying to build the app and run from debugger :
Exception : "Could not find file 'D:\xxxx\bin\Debug\xxx.vshost.exe.config"
I am able to run the generated exe from outside debugger. I am getting the mentioned exception ONLY when trying to debug from VS2008.
First try doing a clean/rebuild. Also try closing Visual Studio and deleting the debug folder completely, then restarting and rebuilding.
Assuming that doesn't do it: to solve your short term problem, try going to the properties of your project, then to the Debug tab, and uncheck "Enable the Visual Studio Hosting Process". This should remove all reliance on the vshost.exe and the config file that gets generated for it. If the error above is your only problem, that should at least let you run in debug mode.
I'm guessing this is a locked file, permission problem, of file corruption problem. I've never heard of anyone having problems with the VSHost except on really slow machines.
I'm not sure what is the reason for the exception but I figured how to fix it.
Basically I had enabled "throw" checkbox under debug->exceptions, and that was what started the problem. Still don't know why vshost.exe looks for a config file by default.
I have faced same problem, It comes when we migrate our code from vs2005 to vs2013 or vs2015, for resolving this problem go in your bin folder in vs solution there you will see vshost.exe reference is missing, remove all reference related to vshost, then rebuild your application. :)
I saw previous answer on stack overflow, so my suggestion is
1. don't try disabling visual studio hosting.
2. don't try to build solution in release mode.
these both will not work.
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.