# ++ERROR > [HTML Version](error_compiler.htm) **\++ERROR _message_ ** This directive outputs a message (as with ++MESSAGE) but also generates a compiler error. Like ++MESSAGE, it is mainly used in conjunction with [Conditional Compilation](conditionalcompilation.htm.md) (in which see Example 2) to make sure that the programmer doesn't overlook and important problem. Example: \++IF TARGET\_PLATFORM = 1 ++MESSAGE Compiling for platform Windows \++ELSE ++ERROR This program only supports Windows - must use /C:TARGET\_PLATFORM=1 \++ENDIF