.NET Core locking files - asp.net-core

Question

I have a ASP.NET Core app. I run the application by running the command
dotnet run
I'm seeing the following error in one out of five situations when I build this ASP.NET Core app.
C:...\error CS2012: Cannot open 'C:...\bin\Debug\netcoreapp1.0\AAA.Web.dll' for writing -- 'The process cannot access the file 'C:...\bin\Debug\netcoreapp1.0\AAA.Web.dll' because it is being used by another process.'
In addition to the above issue, I also see no updates that I make in the CSHTML file. I have to stop the dotnet run command, build the app again and then run the dotnet run command.
How can I fix these issues?

Answer 1

This may also help when running your aspnetcore app in IIS.
Add the following to your csproj:
<Target Name="PreBuild" BeforeTargets="PreBuildEvent">
<Exec Command="echo "App Offline" /a > "$(ProjectDir)app_offline.htm"" />
</Target>
<Target Name="PostBuild" AfterTargets="PostBuildEvent">
<Exec Command="del "$(ProjectDir)app_offline.htm"" />
</Target>

Answer 2

If it is on local and application is running on IIS, then in windows task bar before your date time, there should be a IIS Express Option. select IIS Express, select exit. Try running application again.

Answer 3

In my case, I got the same issue due to dotnet watch run command even after stopping the watch mode. Visual studio reported this error message :
The file is locked by: ".NET core Host (pid)"
killing the process with the pid fixed the issue.

Answer 4

When trying to kill the process using /taskkill /f /pid <number in the error> it was telling me the process didn't even exist.
I simply had to find .NET Core Host in Task Manager and end it there.
This occasionally occurs when I edit a test project on Core 3.0 - not using IIS, it's a class library and a test project in a solution only.

Answer 5

Open the Task Manager, find .NET Core Host, right-click, end task.

Answer 6

The dotnet watch command can track file system changes and edits and compile them in to the running process. This is done by first installing the Microsoft.DotNet.Watcher.Tools package in the tools section of the project.json file. See documentation of its usage here.
Once it is installed, you can then run the app with the command dotnet watch run and make edits while avoiding the manual restarting of the application.

Answer 7

I ended up recycling the Application Pool to get my dlls unlocked.

Answer 8

This has happened to me many times. The issue, at least in my case, has been that I have the application running. So when the compiler tries to update the dll it can't because the dll is locked and in use by the running application. Once I close the application and do the compile again, it works fine.

Answer 9

I may be a bit late to the party here, but for future people reading this question, it would appear that this is a bit of a 'feature' with how VS/core is able to interact with IIS and stop files from being locked:
https://developercommunity.visualstudio.com/content/problem/546858/bin-files-locked-by-iis-worker-process-1.html
It is apparently being investigated and looked into for .net core vnext.

Answer 10

I'm still running into this regularly in VS2017 and VS2019. Hopefully this helps someone.
This is what works every time for me.
If using IISExpress - Stop the Application using the icon in the task bar (near the clock/time)
If using IIS - Stop and Restart the site
OR
In an Admin command prompt run taskkill -F -IM node.exe (Kills all node processes currently running)

Answer 11

100% Working For Me
it is being used by another process .net core
go to task manager (for windows )
Right click .NET Core Host
click End Task
as like see this image

Answer 12

This problem offen when you set AspNetCoreHostingModel to "OutOfProcess"
then you have two solution for problem:
change hosting model to "InProcess"
use below command in CMD
taskkill /f /pid {.netcore hosting pid , show you in error line in visual studio}
For use that command, you do not use "" and {}.

Answer 13

For me, it worked by -
Go to your bin and the environment, take a backup for files, try deleting the folder
D:\CawProjects\EmailAnalytics\APIV1\APIV1\bin\Development
if it does not allow you to delete and says Open/Used somewhere then follow the below process.
Open task manager - find for .net core host and right-click to end the task