MPI_ADD_ERROR_CODE(3)

💖 MPI_ADD_ERROR_CODE 💖

okay bestie, welcome to the Open MPI corner of the manual — this one's page MPI_ADD_ERROR_CODE(3), and it's genuinely a lil cutie. no cap. let's go 🦋

NAME

MPI_Add_error_code — creates a new error code associated with errorclass ✨

---

SYNTAX

C Syntax 🌸

#include <mpi.h>

int MPI_Add_error_code(int errorclass, int *errorcode)

Fortran Syntax 🌸

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_ADD_ERROR_CODE(ERRORCLASS, ERRORCODE, IERROR)
     INTEGER  ERRORCLASS, ERRORCODE, IERROR

Fortran 2008 Syntax 🌸

USE mpi_f08
MPI_Add_error_code(errorclass, errorcode, ierror)
     INTEGER, INTENT(IN) :: errorclass
     INTEGER, INTENT(OUT) :: errorcode
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

---

INPUT PARAMETER

• errorclass — an MPI error class, and it's an integer 💜

OUTPUT PARAMETERS

• errorcode — the error code that a given MPI routine hands back, or an MPI error class. also an integer 🙈
• ierror — Fortran besties only: your error status, integer vibes ✨

---

DESCRIPTION

so basically it creates a brand new error code, ties it to errorclass, and drops its value into errorcode. that's the whole plot. she's simple, she's efficient, she ate 💅

---

NOTES

• there is like, no function to free error codes. why? because nobody expects an application to be out here making them in significant numbers. chill, it's fine 🧚
• whatever value you get back is always greater than or equal to MPI_ERR_LASTCODE. periodt. ⭐

---

ERRORS 😭

Almost all MPI routines return an error value — C routines give it back as the return result of the function, and Fortran routines put it in that last argument. no cap.

Before the error value is returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) is called. If no communication object is associated with the MPI call, then the call is considered attached to MPI_COMM_SELF and will call the associated MPI error handler. When MPI_COMM_SELF is not initialized (i.e., before MPI_Init/MPI_Init_thread, after MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial error handler. The initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/MPI_Comm_spawn_multiple. If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all other MPI functions.

Open MPI includes three predefined error handlers that can be used:

• MPI_ERRORS_ARE_FATAL — causes the program to abort all connected MPI processes. 💀 dramatic but necessary.
• MPI_ERRORS_ABORT — an error handler that can be invoked on a communicator, window, file, or session. When called on a communicator, it acts as if MPI_Abort was called on that communicator. If called on a window or file, acts as if MPI_Abort was called on a communicator containing the group of processes in the corresponding window or file. If called on a session, aborts only the local process.
• MPI_ERRORS_RETURN — returns an error code to the application. the polite one 🫶

MPI applications can also implement their own error handlers by calling:

• MPI_Comm_create_errhandler then MPI_Comm_set_errhandler
• MPI_File_create_errhandler then MPI_File_set_errhandler
• MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init
• MPI_Win_create_errhandler then MPI_Win_set_errhandler

bestie, important: note that MPI does not guarantee that an MPI program can continue past an error. fr fr. plan accordingly 🙈

See the MPI man page for a full list of MPI error codes.

See the Error Handling section of the MPI-3.1 standard for more information.

See also:

• MPI_Add_error_class
• MPI_Error_class

---

Copyright 👑

2003-2026, The Open MPI Community

---

aaand that's the page, bestie 🎀 huge shoutout to The Open MPI Community for the copyright, and this lil drop is dated Sep 10, 2026. iconic behavior honestly. go forth and MPI_Add_error_code responsibly 💖✨🦋