Invalid preprocessor expression
The compiler encountered an invalid preprocessor expression.
The following sample shows some valid and invalid preprocessor expressions:
#if symbol // OK #endif #if !symbol // OK #endif #if (symbol) // OK #endif #if true // OK #endif #if false // OK #endif #if 1 // CS1517 #endif #if ~symbol // CS1517 #endif #if * // CS1517 #endif class x { public static void Main() { } }