File is locked by Visual Studio 2019

user_384556 0
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I have a weird problem in Visual Studio:

if an unhandled exception is thrown during the debugging process I'm not able to build my C# application:

Unable to copy file "C:\Projects\A\bin\A.dll" to "..\..\bin\A.dll". 
  The process cannot access the file '..\..\bin\A.dll' because it is being used 
  by another process.

Could not copy "C:\Projects\A\bin\A.dll" to "..\..\bin\A.dll". 
  Exceeded retry count of 10. Failed. 
  The file is locked by: "Microsoft Visual Studio 2019 (14904)"

Is there a permanent solution to solve this strange error? (my only workaround is currently to restart Visual Studio)

What I tried and not worked for me:

  • VS menu -> Tools -> Options -> Projects and Solution -> Build and Run -> and "set maximum number of parallel builds" to 1.
  • Stop AntiVirus
  • Enable Application experience service (not found in Windows 10)
  • untick VS menu -> Tools -> Options -> Projects and Solution -> General -> Allow parallel project initialization
  • untick Debug -> Options -> Debugging -> General -> Break all processes when one process breaks

It's also not practical to insert Pre-build event scripts in all of my projects! Link: https://blog.ndepend.com/visual-studio-script-saves-time-pain/

Does anyone have a solution to this problem?

locked-files visual-studio-2019 visual-studio c#
9 Answers

What worked for me - Close the Solution, Delete the bin and obj folder, re-open and build.

user_122153200

It's a little bit weird but the problem was caused by the Debug option Use Managed Compatibility Mode! So just untick Debug -> Options -> Use Managed Compatibility Mode and no more files locked errors by Visual Studio!

Remark: The downside of disabling this option is you will get annoying long time consuming evaluation errors by VS! (More information)

user_3845560

Deleting the obj and bin folders were impossible for me, so i had to install Microsoft's Process Explorer to find the application's dll process still running. Killing this process worked for me.

user_88043710

it is a little stupid but: In windows task manager in Process tab, just find Microsoft visual studio <2019>, click "^" to collapse it's child's tree and find "Microsoft Visual Studio XAML Designer" select "Microsoft Visual Studio XAML Designer" and simply end process it before every debug.

user_102092360

Deleting was impossible for me but it turned out that VS2019 kept a debug version of the software running that didn't close automatically when I stopped debugging. In Task manager -> close the running app and I could start the build/debug again.

user_46631850

I have encountered this in a WinForms project in VS2019, where none of the other suggested solutions has worked, and where exiting VS and attempting to delete the affected files was refused by the O/S still claiming the files were open.

The fix that has worked here in this case was to go to Task Manager, and to find and terminate a copy of VBCSCompiler that is being left running even after VS has terminated. It shows up under "Background Processes".

After that, starting VS again worked fine.

user_3617350

Run Clean before Building or use Rebuild option. VS will build it fine. Bit slow , but it works everytime. No VS restart required.

user_171963260

Deleting worked for me as well but only after I force exited the DTSDebugHost from taskmgr for any others that couldn't get it to work.

user_14225300

Simple fix in my case. I already had my application running when I tried to run it again and got this error. Closing it solved my problem.

user_86699790
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