Cannot build .Net Core in WSL with mount volume

Question

Describe the bug

I am using VS Code, WSL and .net core 3.0 preview to build one sample web API project in WSL that is stored in C drive. But It throws an exception with a strange error

"/mnt/c/temp/test/test.csproj" (default target) (1:7) ->
                   (_CreateAppHost target) ->
                     /usr/share/dotnet/sdk/3.0.100-preview9-014004/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(370,5): error MSB4018: The "CreateAppHost" task failed unexpectedly. [/mnt/c/temp/test/test.csproj]
                   /usr/share/dotnet/sdk/3.0.100-preview9-014004/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(370,5): error MSB4018: System.IO.IOException: Invalid argument [/mnt/c/temp/test/test.csproj]
                   /usr/share/dotnet/sdk/3.0.100-preview9-014004/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(370,5): error MSB4018:    at System.IO.MemoryMappedFiles.MemoryMappedView.CreateView(SafeMemoryMappedFileHandle memMappedFileHandle, MemoryMappedFileAccess access, Int64 requestedOffset, Int64 requestedSize) [/mnt/c/temp/test/test.csproj]
                   /usr/share/dotnet/sdk/3.0.100-preview9-014004/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(370,5): error MSB4018:    at System.IO.MemoryMappedFiles.MemoryMappedFile.CreateViewAccessor(Int64 offset, Int64 size, MemoryMappedFileAccess access) [/mnt/c/temp/test/test.csproj]
                   /usr/share/dotnet/sdk/3.0.100-preview9-014004/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(370,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.HostWriter.<>c__DisplayClass2_0.<CreateAppHost>g__RewriteAppHost|0() [/mnt/c/temp/test/test.csproj]
                   /usr/share/dotnet/sdk/3.0.100-preview9-014004/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(370,5): error MSB4018:    at Microsoft.NET.HostModel.RetryUtil.RetryOnIOError(Action func) [/mnt/c/temp/test/test.csproj]
                   /usr/share/dotnet/sdk/3.0.100-preview9-014004/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(370,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.HostWriter.CreateAppHost(String appHostSourceFilePath, String appHostDestinationFilePath, String appBinaryFilePath, Boolean windowsGraphicalUserInterface, String assemblyToCopyResorcesFrom) [/mnt/c/temp/test/test.csproj]
                   /usr/share/dotnet/sdk/3.0.100-preview9-014004/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(370,5): error MSB4018:    at Microsoft.NET.Build.Tasks.CreateAppHost.ExecuteCore() in /_/src/Tasks/Microsoft.NET.Build.Tasks/CreateAppHost.cs:line 68 [/mnt/c/temp/test/test.csproj]
                   /usr/share/dotnet/sdk/3.0.100-preview9-014004/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(370,5): error MSB4018:    at Microsoft.NET.Build.Tasks.TaskBase.Execute() in /_/src/Tasks/Common/TaskBase.cs:line 38 [/mnt/c/temp/test/test.csproj]
                   /usr/share/dotnet/sdk/3.0.100-preview9-014004/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(370,5): error MSB4018:    at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute() [/mnt/c/temp/test/test.csproj]
                   /usr/share/dotnet/sdk/3.0.100-preview9-014004/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.targets(370,5): error MSB4018:    at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask) [/mnt/c/temp/test/test.csproj]

To Reproduce

Steps to reproduce the behavior: 1. Using this version of ASP.NET Core '3.0.100-preview9' both on Window 10 and WSL 2. In Window 10 + cd c:\temp + dotnet new webapi 3. Go to WSL, (/mnt/c/temp) 3. Run dotnet build 4. See error

Expected behavior

Run "dotnet build" successfully and can run/debug application in WSL from VSCode

Answer 1

Setting up dotnet on a fresh installation of Ubuntu (20.04) under WSL 2 on Windows 10 I had the above The "CreateAppHost" task failed unexpectedly. error along with a bunch file-system related permission errors when running dotnet build - however sudo dotnet build worked just fine...

My solution was to close/restart all running WSL instances, from a windows command prompt list all running instances;

C:\> wsl -l --running
Windows Subsystem for Linux Distributions:
docker-desktop-data (Default)
Ubuntu
docker-desktop

Then close the running one you wish to use for dotnet;

C:\> wsl --terminate Ubuntu

And then re-run/re-start the distro;

C:\> wsl -d Ubuntu

And then by magic dotnet build worked without the addition of sudo and also worked via vscode WSL remote plugin... hopefully this simple 'reboot solution' helps someone else!