#error (C# Reference)
#error lets you generate a CS1029 user-defined error from a specific location in your code. For example:
#error Deprecated code in this method.
Note
The compiler treats #error version in a special way and reports a compiler error, CS8304, with a message containing the used compiler and language versions.
Remarks
A common use of #error is in a conditional directive.
It is also possible to generate a user-defined warning with #warning.
Example
// preprocessor_error.cs
// CS1029 expected
#define DEBUG
class MainClass
{
static void Main()
{
#if DEBUG
#error DEBUG is defined
#endif
}
}