Error MSB4019 Microsoft.CSharp.Core.targets not found (under ubuntu 18.04 monodevelop + monogame)


I installed mono, monodevelop 7.3.3 and monogame 3.7.1 for linux on my ubuntu 18.04. I installed templates for monogame under “tools->extensions->gallery->game development” but when i open C# file game.cs it show error in statement “using Microsoft.Xna.Framework” (it doesnt find Xna). i try to manually type in to find what doesn’t recognize and I see that only Microsoft.win32 is recognize with intellisense. when i try to build it it shows error:

/home/mv-whw/.cache/MonoDevelop/7.0/MSBuild/24557_1/Microsoft.CSharp.CurrentVersion.targets(5,5): Error MSB4019: The imported project “/home/mv-whw/.cache/MonoDevelop/7.0/MSBuild/24557_1//Microsoft.CSharp.Core.targets” was not found. Confirm that the path in the declaration is correct, and that the file exists on disk. (MSB4019) (crossPLar.Desktop)

how to fix it?