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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.
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.
When I try to build my project, it returns the following error:
Error 1 Unexpected error creating debug information file 'D:\Documents\Lance\Documents\School\Capstone\GG\GG\obj\Debug\GG.PDB' -- '' GG
I've recently had the misfortune of having my PC restart on me, due to sudden power supply problems (maybe). This is while the project was building, before this problem started.
When the PC came back online I've noticed that the changes I've made to the program prior to the sudden power down was not saved. And, it won't build anymore.
This worked for me:
Shut down VS.NET
Browse to the project in Windows Explorer
Delete the /obj/ folder.
Delete the project outputs (.dll and .pdb) from /bin (not sure if this step is necessary)
Can't hurt but might help: delete the project outputs from any other project /bin folders in the solution that is having issues (wasn't necessary for me)
Restart VS.NET
Rebuild
http://weblogs.asp.net/ssmith/archive/2003/08/12/23755.aspx
As requested, my comment as an answer:
Try cleaning the solution (under the Build menu in VS).
Since the build was interrupted half-way through by your power failure, the file isn't locked -- the build system is probably just in an inconsistent state (which a Clean Solution should fix).
This happens once in a while in my environment and the problem probably has to do with the PDB file being locked (i.e., I'm guessing the last part of the error message is missing in your post). This is how it looks on my machine:
Unexpected error creating debug information file 'c:\dir\obj\file.PDB' -- 'c:\dir\obj\file.PDB: The process cannot access the file because it is being used by another process.'
In my case, cleaning the solution does not solve the problem and restarting is an overkill, so I usually just copy the full name of the pdb file (from the error) and execute this on the command line:
ren c:\dir\obj\file.PDB *.old
This worked for me: Close Visual studio and open visual studio using Run as Administrator and problem was solved.
Not need to restart or delete the file.
Just rename the file and that is enough. If you try to delete the file it will give an error. Better just rename it & it will work. :)
If you are having this problem with a web application, this can happen in the unusual situation that you have used DebugDiag and created a rule that listens on your project's app pool. Deleting the rule prevented this problem from recurring.
This might happen, for example, if you followed these instructions for diagnosing a stack overflow exception in IIS.
If you are working on VM with two user, make sure the other user has not attached all the process while debugging.
Cons of restarting VS:
Clipboard will be lost
Redo/undo will be lost
Files open will be lost
You will loose the tempo
Solution:
Give your Assembly a new name. No cons. Except you will have to rename your assembly back to its original name when you are ready for final deployment. And I think anyone can find how to make it work for the last time :)
Sometimes all the files from \bin folder are used by a running process, i.e. web site on IIS or windows service run automatically after build. In such cases turning off the service or stoping IIS app pool for specific site should also help (like in my case)
Sometimes I run into this problem, when compiling the same project for (very) different targets:
VS2008 and net35
VS2017 and net462
dotnet core 2.0
My guess is, that either bin and/Or obj directory are used by the compiler, but the outputs are not compatible (of course). Solution clean from VS indeed helps.
Often we specify different dll names for the output (e.g. mylib.dll, mylib35.dll) and the issue never happened on those projects.
I have the following problem.
I made an application in C# (using Visual Studio 2010). Everything worked fine.
Then I had to make some changes in a "main.cs". Did those... all fine again.
Then I had to make other changes in same file. Did those... cleaned the solution built it. The problem is that when I run/debug/anything the application I get the same result as I did before I made the changes. I even tried to break the code (called a random function that didn't exist, used wrong syntax), but the result was the same "Build successful" and the old version.
Is there some kind of cacheing mechanism or something? How do I get rid of this problem?
I added prints for the "compile" solution... I can't find the build property.
Try deleting the bin and obj directories in the Visual Studio project directory. The obj directory contains the temporary files used to create the binary while the bin directory contains the binaries for that project. In addition, check if there are any warnings being shown when you build your solution.
I was able to reproduce the same error i.e. build successfully even though the file has not been compiled. The Build Action of the file had not been set to Compile.
The correct Build Action for a code file (main.cs) would be Compile.
According the updated question the file properties does not have the compile option
The reason for this is that the file (main.cs) has not been included in the project, but the "Show all files" button is "on" in the Solution Explorer. The file has not been included in the project (hence not compiled) and the file icon is greyed out in Solution Explorer.
To include this file in the project, right click on add existing item to the project (see following image). In the subsequent dialog select the file (main.cs) and click on the add button.
This should solve your problem.
In future, it is best to keep the "Show All Files" button as "off" to avoid confusion.
Is it possible you have selected the build and run last successful version? Check out my answer to something similar here. If the changes you made broke something and you had checked the boxes and hit yes to the dialog boxes in my answer below then that's most likely the issue.
Cannot see changes I make when I run my application in Visual Studio
Make a backup of your solution.
Delete the .cs files from within the solution explorer. If your program compiles and runs, than you are linked to source folders and not actually using the one in your solution.
I doubt this is it, but worth a try. The other things that came to mind you have already eliminated out with the previous answers.
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.