How to raise a custom error

InterSystems FAQ rubric

If you want to raise an arbitrary custom error in a TRY block, you can pass an exception with a throw as follows. In the following example, a custom error is raised if Stcount is less than 1.

Class User.Test
{

ClassMethod ExceptionTest()
 {
    try
    {
      // : some codes
      if (Stcount<1) {
          throw ##class(%Exception.General).%New("User-defined error", "5001", "location", "Data at location error")
          // User-created errors are 5001 and above
      }
    }
    catch ex
    {
      write "Errors #", ex.Code, ": ", ex.Name, " : ", ex.Location, " ", ex.Data
      return
    }
 }
}

In the above example, if Stcount is less than 1, an error like the following will be output:

USER>do ##class(User.Test).ExceptionTest()
Error #5001: User-defined error: Data at location error

For more information, see the following documentation:
ObjectScript command _THROW

If you want to create an arbitrary status code, do the following:

USER>set st = ##class(%SYSTEM.Status).Error(5001,"This is a user-defined error")

USER>zwrite st
st="0 "_$lb($lb(5001,"This is a user-defined error",,,,,,,,$lb(,"USER",$lb("e^zError+1^%SYSTEM.Status.1^1","e^^^0"))))/* Error #5001: This is a user-defined error */
USER>do $SYSTEM.Status.DisplayError(st)

Error #5001: This is a user-defined error