Hi been using Unity with VSC successfully for over a year now. I had a HDD failure so have reinstalled Unity and VSC. I have installed the Unity debugger and tools on VSC. However when I try to connect the debugger it connects for 2-3 seconds then drops out, no error is reported. I have Unity preferences set to VSC and editor attaching is ticked. Can anyone advise? I’m using Unity 2019.4.7f1 and VSC
Version: 1.47.3
Commit: 91899dcef7b8110878ea59626991a18c8a6a1b3e
Date: 2020-07-23T15:51:39.791Z
Electron: 7.3.2
Chrome: 78.0.3904.130
Node.js: 12.8.1
V8: 7.8.279.23-electron.0
OS: Linux x64 4.15.0-112-generic
Thanks 
To add VSC launch command in my start bar shows /usr/share/code/code --no-sandbox --unity-launch %F
How can I change dotnet 5.0 to default settings? My dotnet --version is 3.1.04 and it installed from Microsoft guide

I deleted the old folder of dotnet 3.1 in usr/share/dotnet and unzip it again in the same path usr/share/dotnet. I can use if before this with mono-project, but maybe Csharp omnisharp extension has updated, and I cannot use it again.
I think Unity extension on VSCode must update too.
My dotnet version now is 5.0. But in vscode, it still shows the output
/home/alpheratz/.vscode/extensions/ms-dotnettools.csharp-1.23.1/.omnisharp/1.37.0/omnisharp/.msbuild/Current/Bin/Microsoft.Common.CurrentVersion.targets(1178,5): Error: The reference assemblies for .NETFramework,Version=v4.7.1 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at .NET SDKs for Visual Studio
The Unity Debugger for VS Code requires mono, which can be installed at Download - Stable | Mono. Otherwise you will see the behavior you’re getting now where it looks like it’s connecting, but really isn’t. It’s trying to run “mono UnityDebug.exe” in ~/.vscode/extensions/unity.unity-debug-2.7.5/bin but can’t, so it just quits.
The notes on the extension don’t make it clear that mono is a requirement, so it may be worth opening an issue at Pull requests · Unity-Technologies/vscode-unity-debug · GitHub.