After diligently working hard on code today I noticed something strange: after ending my debugging session and coming back to my MVC controller I get an actual pop up alert indicating "Object reference not set to an instance of an object". I don't get one, I get a whole cascade of them and VS basically locks up the point of needing a reboot. This seem unusual since I'm not debugging anything and this error is coming up in Visual Studio 2013 itself, not in any code errors or error panels.
What I've done to try to fix this:
Refreshed my database on localhost. This did not fix it.
Rapidly hit the keyboard shortcut to rebuild the project. This works about 75% of the time.
Try to clean the project before the alert cascade show happens. This always fixed it when coupled with a VS restart. If I run the debugger to test my web application it comes back.
This does not come back with other projects.
The code function I'm dealing with is related to quizzes - I've created tested the initial quiz taking function as of a week ago, but now I'm working on a "resume quiz" function. So very similar and some shared methods in the controller.
This is pretty much a hard stop for me since my entire IDE is useless for this part of code. Has anyone run into VS itself saying "object reference not set to an instance of an object"?
Updating for those who come to see this later:
I don't know exactly what was broken, the devenv log didn't show it.
I uninstalled all my extensions and add-ons (just VS Web Essentials, Telerik Testing Studio and Ranorex Test Automation) and then
repaired my VS install.
Lastly, I updated all frameworks in the project via the "Extensions
and Updates" option under Tools in the VS Menu and my problem went away.
Had the same issue with VS2017 and fixed it with
https://stackoverflow.com/a/36056076/3772108
Then I changed the target browser from Chrome to IE. Then F5, wait, stop the whole thing and changed it back to the chrome. Maybe this helps someone too.
I'm porting over a Visual Studio C# solution with many projects and creating a new solution in the Xamarin IDE - all on windows.
I am porting / re-creating 1 project at a time and then compiling. I can compile each project individually but and then I can compile the solution (with some errors).
The problem arises if I try a Rebuild All, then it shows the error:
'Access to the path "[my build path\some.dll]" is denied.'
I have full admin rights and, as I mentioned, I originally could build the dll's so it's not an access issue.
If I try to actually delete the dll's in question, I can't - windows denies me.
If I close Xamarin, I can then delete the file manually. So, I assume, Xamarin still has a 'lock' on the file which won't allow it to be deleted.
Has anyone else seen this and if so, how did you get around it?
If this is a bug, then this makes this nearly unusable.
I just started with Xamarin in Windows as well and am having this problem. A quick fix I found it to switch from Debug over to Release; but this disables your debug output. Closing and reopening Xamarin has also relieved the issue for a few more debug builds.
I have found no rhyme or reason why this is occurring, seems to be at random.
Check the read-only property of the dll on that path, make sure it is not checked. I had the same issue, After unchecking the read-only property, the issue resolved.
Remove all cache in this file C:\Users{user}.nuget\packages And update xamarin.forms
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've got a C# webforms app, that until today had been working just swimmingly.
Now today, all of a sudden, every time I try run the app, I get a file locking error:
Unable to copy file "obj\Debug\MyProject.exe" to "bin\Debug\MyProject.exe". The process cannot access the file "bin\Debug\MyProject.exe" because it is being used by another process.
Googling the error doesn't come up with anything beyond the obvious, i.e. VS thinks the file is locked. And it is definitely Visual Studio itself that locks the file, because when I close VS and reopen it, the project executes fine - the first time. When I try to run it a second time, I get the file locking error.
Closing VS and reopening every time I want to run the app is not a viable workaround! How do I find out what's locking the file, and stop it from getting locked?
EDIT: Another interesting discovery: I don't even have to run the app. Just compiling it once causes the file locking; I cannot compile twice in a row!
This problem is specific to one project in my solution. All other projects work fine and can be executed as many times as I like. It's only this one project that gets itself locked up.
I have found a simple solution which works for me. It goes like this:
When the problem occurs, just change the building configuration at the top (if in “Release” to “Debug” and vice versa), build and then change back to previous configuration and build again.
I suppose that changing the configuration releases the vcshost and devenv.
Well, I solved the problem myself - though I still have no clue why. I decided to isolate the problem by removing all files from the project, then re-adding them and determining that way which file was the source of my trouble. So, one by one I reintroduced files to the project, compiled & cleaned each step of the way... until... I added the last one...
... and everything still worked fine.
I did a compare to the source control of my original .csproj; no real differences. And even when I tried reverting to the previous version of the .csproj, it still worked.
Black magic. If it works, sometimes it's better not to ask why - just accept it and move on...
EDIT: The problem is a recurring one, and I believe I've isolated it to when I have the form designer open of an abstract/generic form at compile time.
Lesson learned: Make sure the Form Designer of any abstract or generic forms or controls is closed before you compile! If not, you have to close VS and reopen!
What we have discovered here, is the following:
In the project properties page, Debug tab, uncheck the "Enable visual studio hosting process".
I am unsure what this property is for, but it does the work once unchecked.
Solved by closing all instances of MSBuild.exe in the windows task manager
Actually you should want "Enable the Visual Studio hosting process" checked. At least for VS2010 anyway. And I also have:
if exist "$(TargetPath).locked" del "$(TargetPath).locked"
if exist "$(TargetPath)" if not exist "$(TargetPath).locked" move "$(TargetPath)" "$(TargetPath).locked"
in the pre-build options. This problem has dogged me for a very long time and it wasn't until John W. mentioned this check box that I even took notice that it existed and low and behold it was already unchecked.
Also notice that -app-vshost.exe runs in the background even when not debugging. Which is what makes it successfully build and run every time I guess. It wasn't running before. And I also tried cleaning out the debug and release folders and changing the target type constantly and nothing worked except as described above. My solution before was to just wait 5 minutes between builds, which got super annoying and time-consuming to get anything done. I haven't seen any change in behavior where it mattered what tabs where open or XNA vs windows form or designers being opened. This issue occurred in 32-bit or 64-bit builds and didn't matter if I killed an app with ALT-F4 or killing it with task manager, which would, in theory, not allow the app to close or release resources. At first I thought it was a garbage collection issue.
I have overcome this problem by renaming the locked file (using Windows Explorer). I was not allowed to delete the file, but renaming the locked file works!
Little late to answer, but I solved this by going to the properties of the project > tab "Debug" > unchecked "Enable the Visual Studio hosting process" option.
I solved this by deleting the folder bin\Debug and, possibly, restarting VS
Run this command from the Run box:
net stop iisadmin /y
and then
iisreset
worked for me.
vs 2003
For me, it was a Windows Service that was installed and running. Once I stopped it, the build was successful.
I had a similar error but during the deployment of the UWP application. Finally, I found out the process that used a file that caused this error and stopped it. Credits to this link. Copy-pasted version is below.
How to Solve the Issue?
One of the easiest ways to handle locked files or folders is to use Microsoft Sysinternals Process Explorer.
Identify what program is using a file
Using Process Explorer there is a simple way to find the program:
Open Process Explorer (running as administrator).
On the toolbar, find the gunsight icon on the right.
Drag the icon and drop it on the open file or folder that is locked.
The executable that is using the file will be highlighted in the Process Explorer main display list.
Identify which handle or DLL is using a file
Open Process Explorer (running as administrator).
Enter the keyboard shortcut Ctrl+F.
Alternatively, click the “Find” menu and select “Find a Handle or DLL”.
A search dialog box will open.
Type in the name of the locked file or other file of interest.
Partial names are usually sufficient.
Click the button “Search”.
A list will be generated.
There may be a number of entries.
And then kill this process.
Unfortunately none of the answers worked for me. This is what solved it:
Win Key + R and run resmon.exe. There you'll find the EXE process that VS claims to be using the file. Right click and end the process. Although you might get an Access Denied error message, it will be suspended and you'll be able to build again.
Recently ran into this problem when attempting to build a solution I am working on (not just a winforms proj).
In addition to build failure, I noticed that cleaning projects would quietly fail (checking the bin folder showed that the files had not actually been erased) and closing the Visual Studio did not end the devenv process - rather, it caused it to crash. Windows recovery process would then restart the Visual Studio.
After some trial and error, I found the problems only happened to me when I opened the solution from the "Recent" menu on starting up VS.
Opening the solution from File >> Open >> Project/Solution found it working as per usually.
Currently no idea why - will keep looking into this but for now, at least I can work!
Just check the references and remove the self-reference to the project.
Explanation: My problem started after creating a custom control and drag and drop it to the toolbox palette for use it in design forms. First appeared a warning saying that there was a redundance between the custom control source file (.cs) and the projects executable (.exe). On executing/debugging appeared the error: unable to access the (.exe) because it's being used (and it was true).
I literally removed the whole source code regarding the custom control and the problem still remained, until I checked out the references and it was referencing itself in order to be "able to" get the former custom control. I removed the reference and done!!
I had the same issue on my Xamarin application in visual studio and it was resolved by unplugging my test mobile device. The application was closed and the debugger was stopped but the error was still happening when trying to build or rebuild the solution. It only stopped after i unplugged the device because i had to receive a call.
Just to throw in my 2 cents. My issue was solved by opening Task Manager and killing the application. It was running in the background without any indication that it was running at all (no item in the task bar, no ui, nothing), but I am not sure why this happened. Obviously the debugger was not running and I only had a single instance of VS opened at the time. It amazes me that this is still happening in this VS 2017.
Perhaps I can add a build step that looks for the application running the background and kills it before starting the new one.
I had the same issue and could not rectify by using any of the methods mentioned in previous answers. I resolved the issue by killing all instances of "SSIS Debug Hist (32 bit)" in task manager and now working as normal.
I had this issue (and its an issue I have seen in other places not just VS).
It's caused by Dropbox (in my case). After editing some code and hitting run, sometimes dropbox immediately locks the file (so it can process it).
Solution 1.
Just hit run again
Solution 2.
Pause dropbox. (not good if your using dropbox as your cloud backup)
Solution 3.
Remove the build folder from dropboxes sync list.
Deleting Obj, retail and debug folder of the .NET project and re-building again worked for me.
This got me stuck for over two days, had to reclone the project and save the project folder in a different name, but today I found the solution from a microsoft dev forum.
solution:
Create a pre-build action in your project by going to project properties (right-click on the project in the solution explorer, and select the Properties option), select the Build Events tab. Add this code:
if exist "$(TargetPath).locked" del "$(TargetPath).locked"
if not exist "$(TargetPath).locked" move "$(TargetPath)" "$(TargetPath).locked"
This code will copy the file to a different name, and allows the build to continue successfully.
How is your web app configured? Does it run under Cassini (the tray web server) or IIS?
This shouldn't happen normally though. I think ProcessExplorer can tell you what files a process has locked. If not process explorer one of the other sysinternals tools.
One thing to try before even downloading one of the SI tools is to stop the Cassini web server, and seeing if that frees up the file.
What worked for me was restarting IIS
i had this same problem as well. changing the debug/release config didn't do the trick. at least not without building in between.
in my solution (winform) it was solved by opening the mainform of the winform in the designer. switching to code (F7). Then closing the code, closing the designer of the winform and rebuild all (ctrl-shift-B). This worked for me.
seems like some kind of handle from within the winform app (which runs a backgroundworker) still had a file handle on some of the other libraries used.
I had two instances of Visual Studio opened the same solution.
In my case there were some vstest processes running (with various names but all containing the string vstest). I had to terminate them in taskmgr.
Same error, solved by updating Google Nuget support packages
When I ended the process .Net Core Host, everything built fine. I didn't have to close Visual Studio or do change anything else.
For those who are developing in VS with Docker, restart the docker for windows service and the problem will be solved immediately.
Before restarting docker I tried all the mentioned answers, didn't find a msbuild.exe process running, also tried restarting VS without avail, only restarting docker worked.
One more solution: when the files get locked, blocking process is reported (something like "ServiceHub.Host.CLR.x64 (7764)") with it's id in parentheses.
To get rid of the process, open PowerShell (x + Win + I) and type: "Stop-Process -Id idNumber".
I recently ran into the issue when deploying to Service Fabric. The error is implying a 'file' is in use, however, I found that the port was being used by another IDE. By stopping a running service which was already hosting on the port, I was able to stop this exception from occurring.