From 15f1c2d9600562624fb9a9a82f61d4a5b080fceb Mon Sep 17 00:00:00 2001
From: Stan Gerald Moore <stamoor@sandia.gov>
Date: Thu, 18 Nov 2021 08:50:09 -0700
Subject: [PATCH] Fix inaccurate error message

---
 doc/src/dump_modify.rst | 4 +++-
 src/dump.cpp            | 2 +-
 src/dump.h              | 5 ++---
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/doc/src/dump_modify.rst b/doc/src/dump_modify.rst
index da7ccffeb2..88b375ecb6 100644
--- a/doc/src/dump_modify.rst
+++ b/doc/src/dump_modify.rst
@@ -561,7 +561,9 @@ The dump *local* style cannot be sorted by atom ID, since there are
 typically multiple lines of output per atom.  Some dump styles, such
 as *dcd* and *xtc*, require sorting by atom ID to format the output
 file correctly.  If multiple processors are writing the dump file, via
-the "%" wildcard in the dump filename, then sorting cannot be
+the "%" wildcard in the dump filename and the *nfile* or *fileper*
+keywords are set to non-default values (i.e. the number of dump file
+pieces is not equal to the number of procs), then sorting cannot be
 performed.
 
 .. note::
diff --git a/src/dump.cpp b/src/dump.cpp
index 9ca7e61e76..2917099ff9 100644
--- a/src/dump.cpp
+++ b/src/dump.cpp
@@ -228,7 +228,7 @@ void Dump::init()
   if (sort_flag) {
     if (multiproc > 1)
       error->all(FLERR,
-                 "Cannot dump sort when multiple dump files are written");
+                 "Cannot dump sort when 'nfile' or 'fileper' keywords are set to non-default values");
     if (sortcol == 0 && atom->tag_enable == 0)
       error->all(FLERR,"Cannot dump sort on atom IDs with no atom IDs defined");
     if (sortcol && sortcol > size_one)
diff --git a/src/dump.h b/src/dump.h
index 681ce88c96..468b007096 100644
--- a/src/dump.h
+++ b/src/dump.h
@@ -173,10 +173,9 @@ E: Dump file MPI-IO output not allowed with % in filename
 This is because a % signifies one file per processor and MPI-IO
 creates one large file for all processors.
 
-E: Cannot dump sort when multiple dump files are written
+E: Cannot dump sort when 'nfile' or 'fileper' keywords are set to non-default values
 
-In this mode, each processor dumps its atoms to a file, so
-no sorting is allowed.
+Can only dump sort when the number of dump file pieces using % in filename equals the number of processors
 
 E: Cannot dump sort on atom IDs with no atom IDs defined