MPI_ERROR_CLASS(3)

🎀 NAME 🎀

okay bestie, welcome to the Open MPI manual page for MPI_ERROR_CLASS(3) — the page about the little function that converts an error code into an error class. MPI_Error_class is literally here to do that one glow-up, no cap. 💖

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✨ SYNTAX ✨

💻 C Syntax 💻

#include <mpi.h>

int MPI_Error_class(int errorcode, int *errorclass)

🧚 Fortran Syntax 🧚

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

🦋 Fortran 2008 Syntax 🦋

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

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🌸 INPUT PARAMETER 🌸

• errorcode — the error code an MPI routine returned to you. that's the input, bestie. 🫶

🌟 OUTPUT PARAMETERS 🌟

• errorclass — the error class associated with errorcode. it's giving “matching set” energy. ✨
• ierror — Fortran only: the error status, and yes, it's an integer. 💅

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💖 DESCRIPTION 💖

Here's the tea: the function MPI_Error_class maps each standard error code (error class) onto itself. lowkey iconic — standard error codes get to be their own main character, periodt. 👑

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🔥 ERRORS 🔥

okay so error handling in MPI is a whole journey, but here's the rundown. Almost all MPI routines return an error value; C routines return it as the return result of the function, and Fortran routines return it in the last argument.

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. 💀
• 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. 🫶

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

⚠️ Note that MPI does not guarantee that an MPI program can continue past an error. like, fr fr, do not assume it can keep going. 💀

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.

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💜 SEE ALSO 💜

• MPI_Error_string — the SEE ALSO reference, bestie. 🦋

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🎀 COPYRIGHT 🎀

2003-2026, The Open MPI Community 🫶

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okay bye bestie 💋 — you got this, map those error codes, slay, and keep your handlers cute 🧚‍♀️✨ — source/version: Open MPI · date: Sep 11, 2026.