Today I got a strange error.

Error CS0518: Predefined type ‘System.Object’ is not defined or imported

Strangely, all nant related tasks just work as accepted.

After a little googling i’ve found a solution here, that says that i need to reference mscorlib. I did that and the error was gone.

Then I opened my project preferences and saw that a checkbox was check, which told not to reference mscorlib. After unchecking the checkbox, the day was saved.

do not reference mscorlib

The screenshot shows preferences in SharpDevelop 3.1