Can't start an simple app

[vTete]

I'm on a raspberry 3 with Raspbian and it's impossible to run an app.

Any Idea ?

[TheAwesome98-Real]

translation to english if anyone needs it: The imported project "/home/pi/.cache/MonoDevelop/7.0/MSBuild/1662_1//Microsoft.CSharp.Core.Targets" was not found. Confirm that the expression in the Import declaration "/Microsoft.CSharp.Core.Targets" is correct, and that the file exists on disk

[smetronic]

I had experience the same issue but after doing the below steps the error went away and I was able to run the code:

sudo apt install apt-transport-https dirmngr gnupg ca-certificates
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb https://download.mono-project.com/repo/debian stable-raspbianbuster main" | sudo tee /etc/apt/sources.list.d/mono-official-stable.list
sudo apt update

sudo apt install mono-devel
sudo apt install mono-complete

sudo apt-get install -y mono-xbuild
sudo apt-get install gtk-sharp2

sudo apt install apt-transport-https dirmngr
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb https://download.mono-project.com/repo/debian vs-raspbianstretch main" | sudo tee /etc/apt/sources.list.d/mono-official-vs.list
sudo apt update

Goto project options -> Run -> Default -> Disable Run on external console & Pause console output

[yanderemine54]

It sadly didn't work for me