$ msbuild -toolsversion:Current ConsoleApp1.csproj
Microsoft (R) Build Engine version 15.9.20.62856 for .NET Framework
Copyright (C) Microsoft Corporation. All rights reserved.

MSBUILD : error MSB1040: ToolsVersion is not valid. The tools version "Current" is unrecognized. Available tools versions are "2.0".
Switch: Current

$ msbuild -toolsversion:Current ConsoleApp1.csproj
Microsoft (R) Build Engine version 15.9.20.62856 for .NET Framework
Copyright (C) Microsoft Corporation. All rights reserved.

MSBUILD : error MSB1040: ToolsVersion is not valid. The tools version "Current" is unrecognized. Available tools versions are "2.0".
Switch: Current

$ msbuild -toolsversion:2.0 ConsoleApp1.csproj
...
error MSB4019: The imported project "/usr/lib64/mono/2.0/Microsoft.CSharp.targets" was not found. Confirm that the path in the <Import> declaration is correct, and that the file exists on disk.