If a run time error occurs during execution then KCML will halt and display a message box showing the error code, the line and statement number and a summary of the error.

When RETURN is pressed KCML will switch to the debug window in the Workbench showing the program text with the current statement centered and in reverse video. The error code, the line number and statement number and the text of the error message are displayed at the bottom of the screen on the status line.