Unable to copy file reference.dll to bin/reference.dll. The process cannot access the file reference.dll because it is being used by another process

Question

For one of my ASP.NET 3.5 applications, every single time I try to build the web app, it throws the following build errors in Visual Studio 2008:

Error 165 Unable to copy file "C:\InOne\Common\DexProcessor\bin\Debug\DexProcessor.dll" to "bin\DexProcessor.dll". The process cannot access the file 'bin\DexProcessor.dll' because it is being used by another process. InVision2 Error 166 Unable to copy file "C:\InOne\Common\DexParser\bin\Debug\InOne.DexParser.dll" to "bin\InOne.DexParser.dll". The process cannot access the file 'bin\InOne.DexParser.dll' because it is being used by another process. InVision2 Error 167 Unable to copy file "C:\InOne\Common\AlertProcessor\bin\Debug\InOne.Invision.AlertProcessing.dll" to "bin\InOne.Invision.AlertProcessing.dll". The process cannot access the file 'bin\InOne.Invision.AlertProcessing.dll' because it is being used by another process. InVision2 Error 168 Unable to copy file "C:\InOne\Common\InVision.BusinessLogic\bin\Debug\InVision.BusinessLogic.dll" to "bin\InVision.BusinessLogic.dll". The process cannot access the file 'bin\InVision.BusinessLogic.dll' because it is being used by another process. InVision2 Error 169 Unable to copy file "C:\InOne\Common\InVision.Common\bin\Debug\InVision.Common.dll" to "bin\InVision.Common.dll". The process cannot access the file 'bin\InVision.Common.dll' because it is being used by another process. InVision2 Error 170 Unable to copy file "C:\InOne\Data\bin\Debug\InVision.Data.dll" to "bin\InVision.Data.dll". The process cannot access the file 'bin\InVision.Data.dll' because it is being used by another process. InVision2 Error 171 Unable to copy file "C:\InOne\Common\InVision.DataAccessLayer\bin\Debug\InVision.DataAccessLayer.dll" to "bin\InVision.DataAccessLayer.dll". The process cannot access the file 'bin\InVision.DataAccessLayer.dll' because it is being used by another process. InVision2 Error 172 Unable to copy file "C:\InOne\Common\InVision.DataAccessLayer.SqlClient\bin\Debug\InVision.DataAccessLayer.SqlClient.dll" to "bin\InVision.DataAccessLayer.SqlClient.dll". The process cannot access the file 'bin\InVision.DataAccessLayer.SqlClient.dll' because it is being used by another process. InVision2

This just started happening a week ago and is very annoying... I have to go into the web app's bin folder and delete the pdb files and then it'll let me delete the dll's most of the time. Every once in a while it doesn't let me so I have to close Visual Studio and then it lets me delete them. I checked and it's Visual Studio (devenv) that is locking the dll's. Rebooting the machine doesn't help.

This is really reducing my productivity, is there anything I can do to resolve this?

As mentioned, Visual Studio 2008 (devenv.exe) is the process locking the DLLs.

I noticed something... When it compiles successfully, it's copying all the DLLs into the bin folder, then they are all deleted, then a new set are copied into the bin. When it isn't successfull, the first set of DLLs are copied in, then it fails. So it seems to be using the bin folder for 2 things when it should only be for 1. Does this help??

score 19 · Accepted Answer · edited Jun 08 '12 at 07:18

19

The issue ended up being that in the web.config someone had added:

hostingEnvironment shadowCopyBinAssemblies="false"

After commenting this out, everything started building ok. What a nightmare!!

edited Jun 08 '12 at 07:18

AMissico

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answered Sep 08 '09 at 18:14

Justin

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score 13 · Answer 2 · answered Jul 13 '09 at 18:58

13

Use ProcessExplorer to find out what process has the file open and go from there.

If a process is currently using those DLL, you can't delete and re-write it. You'll have to kill or otherwise stop the process using those DLLs while you compile.

answered Jul 13 '09 at 18:58

Ben S

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score 12 · Answer 3 · edited Dec 11 '11 at 16:21

12

I have battled this issue FOR YEARS!

Have you tried adding this to your PREBUILD Event?

if exist "$(TargetPath).locked" del "$(TargetPath).locked"
if exist "$(TargetPath)" if not exist "$(TargetPath).locked" move "$(TargetPath)" "$(TargetPath).locked"

See this for more info: http://nayyeri.net/file-lock-issue-in-visual-studio-when-building-a-project

Here's another thread, with more things to try...

http://social.msdn.microsoft.com/forums/en-US/Vsexpressinstall/thread/5b71eb06-5047-483d-8fd3-b75c102d41e9/?prof=required

edited Dec 11 '11 at 16:21

Leo

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answered Jun 30 '10 at 16:12

Developer22222222

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The first URL is broken; fyi. – FMFF Aug 06 '15 at 16:45

score 10 · Answer 4 · edited Jun 09 '15 at 17:45

What worked for me is the following pre-build event:

if exist "$(TargetPath).locked.bak" del "$(TargetPath).locked.bak"
if exist "$(TargetPath).bak" del "$(TargetPath).bak"
if exist "$(TargetPath).locked" ren "$(TargetPath).locked" "$(TargetFileName).locked.bak"
if exist "$(TargetPath)" ren "$(TargetPath)" "$(TargetFileName).bak"

What I have noticed in my case is that the 2 files are being created and can not be deleted. You can, however, rename them (and they are still in use if you try to delete them). On a next build, the renamed files are no longer in use (lock removed) and they can be deleted, which is what the above script does, after which it can safely rename the new locked files so there will be no problems in generating the build output.

The other pre-build events posted here and in other places did not help me a lot (they worked only for one extra build or only a few before the problem arose again). So now I am currently using the one posted above for my debugging purposes.

I think the target of the `ren` commands needs to use `$(TargetFileName)` since the second parameter to `ren` is not supposed to include the path. — Jeremy Stein, Sep 28 '11 at 16:29

score 4 · Answer 5 · answered Oct 27 '10 at 17:26

I just wanted to say that this problem started with me today. (VS 2010, C#) I have been working on this program for a month without this problem, now today it started. I start VS, change code, compile and test and quit program. Make another change, compile and BOOM Unable to copy file "obj\x86\Debug\progname.exe" to "bin\Debug\progname.exe" because if is being used by another process.

ProcExp shows only Visual Studio (actually devenv.exe) using this file. There is only one instance of VS running. There are two listing on my debug\progname.exe, one is a Type DLL, the other is a Type handle.

Using devenv /ResetSettings did not resolve anything, but wasted 10 minutes putting everything back to my desired view.

Using the PREBUILD events rename trick mentioned above solves the problem for a couple of changes, but on the next change the "exe.locked" file is locked and cannot be deleted. Then the rename fails.

The debug\progname.exe file name remains locked even after closing the project.

Closing VS, manually delete the files in the debug folder, opening VS and my solution, then Build->Clean Solution seems to work for me, at least its working now after I did all of that stuff.

Hope this helps -rwg

Craig Nichols · Answer 6 · 2010-12-06T23:01:18.313

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I didn't have any luck with the pre-build events unfortunately. What worked, in typical IT Crowd fashion, was to quit Visual Studio and reopen it.

edited Dec 06 '10 at 23:01

answered Dec 06 '10 at 22:50

Craig Nichols

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This didn't solve it for me, but a restart of my Win7 virtual machine did it. ;-) – Akku Feb 05 '13 at 12:21

score 2 · Answer 7 · edited Jul 10 '12 at 14:34

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If you have Visual Nunit, it must be locking dll file.

Close VS
Go to taks manager , kill the Visual Nunit process
Now open VS and build the project

edited Jul 10 '12 at 14:34

Taryn

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answered Jul 10 '12 at 14:22

Rajesh Toleti

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score 2 · Answer 8 · answered Jun 29 '11 at 10:47

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Easy fix for Windows 7: Start the service "Application Experience" . Search for "Services" in "Control Panel".

-Martin

answered Jun 29 '11 at 10:47

Martin Lütken

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Don't know what this is supposed to do. Doesn't work for me :( – willem Apr 09 '13 at 07:12

score 1 · Answer 9 · answered Sep 08 '09 at 07:44

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Hi I'm facing the same issue for a little while. It's very annoying.

I have an easier yet not so efficient solution for the problem. Cleaning the project or solution solves the problem.

answered Sep 08 '09 at 07:44

I had the same problem with a WinForms application; Cleaning the project indeed solved the issue. Very strange - let's hope that this bug has disappeared from VS2010. – Pierre Arnaud Nov 04 '09 at 12:53
Lol. Sorry, this bug is still in VS2012. – willem Apr 09 '13 at 07:12

score 1 · Answer 10 · answered Sep 19 '11 at 09:17

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Just go to \Debug\bin and delete all .dll files.

Working great for me.

answered Sep 19 '11 at 09:17

learn_andrd

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score 1 · Answer 11 · answered Jan 17 '12 at 11:01

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I had this issue on a web project with System.Web.Extensions.dll from the Microsoft Reference Assemblies folder. Setting "Copy Local" to false in the reference properties fixed it.

answered Jan 17 '12 at 11:01

tags2k

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score 0 · Answer 12 · edited May 23 '17 at 12:34

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I had similar issue and was able to resolve it by changing the 'AssemblyInfo.cs'

Visual Studio build fails: unable to copy exe-file from obj\debug to bin\debug

edited May 23 '17 at 12:34

Community

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answered Apr 14 '12 at 15:48

lulalala

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score 0 · Answer 13 · answered Jul 13 '09 at 18:58

You could download the excellent SysInternals Handle program. This will tell you which processes have a lock on the files concerned.

If it is an external program (e.g. virus scanner/indexer) then this should help. If it just reports Visual Studio (devenv.exe) as the culprit, then it will be of less help!

score 0 · Answer 14 · answered Jul 13 '09 at 18:59

I'm assuming you already know it's VS2008 which is locking the files. You can try running MSBuild from the command line and see if the problems disappear. Unfortunately Visual Studio can keep files locked when it shouldn't, in some hard-to-predict scenarios.

score 0 · Answer 15 · answered Jul 13 '09 at 19:14

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File locks are just part of working with Visual Studio. There aren't any great ways to get around this problem.

answered Jul 13 '09 at 19:14

Chris Ballance

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Hi guys. To the first two, I already checked and it's Visual Studio that is locking the files. To Chris, how can that be an answer?? Pretty much everytime I build the web project it fails because the referenced project dll's that are being copied to the web bin are in use by Visual Studio. This means that I need to close and reopen Visual Studio in order to build almost every time... this is not a solution! This is not happening in under solutions or project so it's something specific to this one web project, so saying this is just part of Visual Studio is crap... – Justin Jul 13 '09 at 19:42
Flip the switch on the "copy assemblies locally" option – Chris Ballance Jul 13 '09 at 20:28
1

Thanks that gets me close. The only build error left is: "Unable to copy obj\debug\web.dll to bin\web.dll. The process cannot access the file because bin\web.dll because it is being used by another process." – Justin Jul 13 '09 at 21:49

score 0 · Answer 16 · answered Jul 13 '09 at 20:01

0

There was a specific bug in Visual Studio 2008 which was fixed in SP1 which may be your issue. It occurs when you reference an embedded JavaScript file and causes the problem you are seeing. See here for more details.

answered Jul 13 '09 at 20:01

Jon

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score 0 · Answer 17 · answered Dec 14 '12 at 17:06

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Happened to me just now. Had to kill all devenv.exe processes (there were 3 of them after closing VS 2010 window).

answered Dec 14 '12 at 17:06

Mauricio Ramalho

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score 0 · Answer 18 · answered Mar 22 '13 at 10:53

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Delete the binaries from the bin\Debug folder and recompile them. This works for me!!!

answered Mar 22 '13 at 10:53

Subbu

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score 0 · Answer 19 · answered Jul 18 '13 at 07:21

This issue commonly occurs when you change your project from one directory to another . For the Shadow copy error you might have added this line in your web.config.To fix this follow the following

In your web.config file if there is something like

<hostingEnvironment shadowCopyBinAssemblies="false" />

change that into

<hostingEnvironment shadowCopyBinAssemblies="true" />

or remove it .Then it will work fine

score 0 · Answer 20 · answered Aug 28 '14 at 17:11

I was using Visual Studio 2012 when this started happening on a 7 year old solution (for the second or third time: I've been to this question before).

I tried the various voodoo. I cleaned the solution. Didn't work. I restarted Visual Studio. Didn't work. I was confident that last one would work, because that is the voodoo that worked last time.

Ultimately, I remembered a security update had installed last night and was configured when I started my machine this morning - (Connected or not? No Idea) - So, I restarted Windows, and voila, it all worked like magic again.

Thanks MS for more mind mincing.

score 0 · Answer 21 · answered Sep 30 '14 at 10:52

0

I also face this problem. First i try to delete contentious .dll but it shows Access denied, then i close my VS and after open, it works fine.

answered Sep 30 '14 at 10:52

Mehedi hasan

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score 0 · Answer 22 · answered Jun 04 '15 at 19:28

Similar to Benoit's answer but doesn't require any tool installation, you can use tasklist (task manager) command at the command line with the '/m' switch to get a list of processes using the dll:

tasklist /m mylocked.dll

I saw some posts indicating you have to do it from the directory of the offending dll, but I haven't found that to be the case.

score 0 · Answer 23 · answered Aug 14 '10 at 08:24

0

I did had simillar problem solution for me was to look at the *.csproj file and under i found missing file so and below was correct one so i just removed lines and it worked straight away

answered Aug 14 '10 at 08:24

Marcin

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score 0 · Answer 24 · answered Aug 09 '16 at 13:44

0

you can also delete bin and obj folders in all projects in solution then rebuild solution.

answered Aug 09 '16 at 13:44

HamidReza

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score 0 · Answer 25 · answered Oct 15 '10 at 10:06

Removing the following lines from my app.config solved this for me - I'm using VS2010.

<runtime>
  <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
          <assemblyIdentity name="nunit.framework" publicKeyToken="96D09A1EB7F44A77" culture="neutral"/>
          <bindingRedirect oldVersion="0.0.0.0-2.5.7.10213" newVersion="2.5.7.10213"/>
      </dependentAssembly>
  </assemblyBinding>
</runtime>

score 0 · Answer 26 · answered Oct 20 '10 at 10:00

0

Check if the user dll and the application referencing the dll target the same .NET framework. I had a case where the frameworks were different which caused this problem.

answered Oct 20 '10 at 10:00

sterimick

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score 0 · Answer 27 · answered May 14 '17 at 20:03

0

open your project in explorer click the property of the bin folder and uncheck the read only property this one works in my xamarin forms project

answered May 14 '17 at 20:03

Riyas K Salim

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score 0 · Answer 28 · answered Jun 13 '18 at 07:06

0

I finally how fix it. It Occures because the first debug exe still running. So , go to Task Manager -> Process Tab -> [your project name exe] end the exe process

answered Jun 13 '18 at 07:06

Sanket Parchande

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score 0 · Answer 29 · edited Nov 27 '12 at 16:11

The file cannot be deleted, fortunately can be renamed and moved. So I created prebuild batch (using date and time as random string, there can be easier ways):

For /f "Tokens=2,3,4 Delims=/. " %%i In ("%Date%") Do @(
  Set Month=%%i& Set Day=%%j& Set Year=%%k
)

set ActDate=%Year%-%Month%-%Day%

For /f "Tokens=1,2,3 Delims=/.:, " %%i In ("%Time%") Do @(
  Set Hour=0%%i& Set Min=%%j& Set Sec=%%k
)

set ActTime=%Hour:~-2,2%-%Min%-%Sec%

move c:\MyProject\bin\Debug\myproject.exe c:\garbage\%ActDate%_%ActTime%_myproject.exe

score 0 · Answer 30 · answered Jan 28 '19 at 08:39

Encountered this problem. Got to know that I was already running the project through git bash. Stopped it. And now its working fine.

Hence there's a possibility if you have been running the same project from anywhere in your local and this error occur. So stop that running program and do it again.

Shakeer Hussain · Answer 31 · 2021-02-21T22:44:27.847

0

I have resolved error by Terminate .exe under TaskManager --> details.

Now build your solution

edited Feb 21 '21 at 22:44

answered Feb 21 '21 at 19:10

Shakeer Hussain

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score 0 · Answer 32 · answered Mar 06 '12 at 01:53

0

This happens to me sometimes when using Visual Nunit for unit tests.

It seems the process 'VisualNunitRunner.exe' locks the .dll files in the destination directory.

I used Unlocker to find the process, kill it or unlock the files.

answered Mar 06 '12 at 01:53

warrickh

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Unable to copy file reference.dll to bin/reference.dll. The process cannot access the file reference.dll because it is being used by another process

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