diff --git a/src/COMPRESS/dump_atom_gz.cpp b/src/COMPRESS/dump_atom_gz.cpp
index 73f1ddf5a2..d4edb07a3a 100644
--- a/src/COMPRESS/dump_atom_gz.cpp
+++ b/src/COMPRESS/dump_atom_gz.cpp
@@ -72,7 +72,7 @@ void DumpAtomGZ::openfile()
         ++numfiles;
       } else {
         if (remove(nameslist[fileidx]) != 0) {
-          error->warning(FLERR, fmt::format("Could not delete {}", nameslist[fileidx]));
+          error->warning(FLERR, "Could not delete {}", nameslist[fileidx]);
         }
         delete[] nameslist[fileidx];
         nameslist[fileidx] = utils::strdup(filecurrent);
diff --git a/src/COMPRESS/dump_atom_zstd.cpp b/src/COMPRESS/dump_atom_zstd.cpp
index 430deda177..561c784739 100644
--- a/src/COMPRESS/dump_atom_zstd.cpp
+++ b/src/COMPRESS/dump_atom_zstd.cpp
@@ -80,7 +80,7 @@ void DumpAtomZstd::openfile()
         ++numfiles;
       } else {
         if (remove(nameslist[fileidx]) != 0) {
-          error->warning(FLERR, fmt::format("Could not delete {}", nameslist[fileidx]));
+          error->warning(FLERR, "Could not delete {}", nameslist[fileidx]);
         }
         delete[] nameslist[fileidx];
         nameslist[fileidx] = utils::strdup(filecurrent);
diff --git a/src/COMPRESS/dump_cfg_gz.cpp b/src/COMPRESS/dump_cfg_gz.cpp
index 25328797dd..277db7dd23 100644
--- a/src/COMPRESS/dump_cfg_gz.cpp
+++ b/src/COMPRESS/dump_cfg_gz.cpp
@@ -74,7 +74,7 @@ void DumpCFGGZ::openfile()
         ++numfiles;
       } else {
         if (remove(nameslist[fileidx]) != 0) {
-          error->warning(FLERR, fmt::format("Could not delete {}", nameslist[fileidx]));
+          error->warning(FLERR, "Could not delete {}", nameslist[fileidx]);
         }
         delete[] nameslist[fileidx];
         nameslist[fileidx] = utils::strdup(filecurrent);
diff --git a/src/COMPRESS/dump_cfg_zstd.cpp b/src/COMPRESS/dump_cfg_zstd.cpp
index 0ea92f3807..defee75ee8 100644
--- a/src/COMPRESS/dump_cfg_zstd.cpp
+++ b/src/COMPRESS/dump_cfg_zstd.cpp
@@ -82,7 +82,7 @@ void DumpCFGZstd::openfile()
         ++numfiles;
       } else {
         if (remove(nameslist[fileidx]) != 0) {
-          error->warning(FLERR, fmt::format("Could not delete {}", nameslist[fileidx]));
+          error->warning(FLERR, "Could not delete {}", nameslist[fileidx]);
         }
         delete[] nameslist[fileidx];
         nameslist[fileidx] = utils::strdup(filecurrent);
diff --git a/src/COMPRESS/dump_custom_gz.cpp b/src/COMPRESS/dump_custom_gz.cpp
index 9ed5a10b02..844cfac1c3 100644
--- a/src/COMPRESS/dump_custom_gz.cpp
+++ b/src/COMPRESS/dump_custom_gz.cpp
@@ -72,7 +72,7 @@ void DumpCustomGZ::openfile()
         ++numfiles;
       } else {
         if (remove(nameslist[fileidx]) != 0) {
-          error->warning(FLERR, fmt::format("Could not delete {}", nameslist[fileidx]));
+          error->warning(FLERR, "Could not delete {}", nameslist[fileidx]);
         }
         delete[] nameslist[fileidx];
         nameslist[fileidx] = utils::strdup(filecurrent);
diff --git a/src/COMPRESS/dump_custom_zstd.cpp b/src/COMPRESS/dump_custom_zstd.cpp
index 073e39a87e..d097b29ad1 100644
--- a/src/COMPRESS/dump_custom_zstd.cpp
+++ b/src/COMPRESS/dump_custom_zstd.cpp
@@ -79,7 +79,7 @@ void DumpCustomZstd::openfile()
         ++numfiles;
       } else {
         if (remove(nameslist[fileidx]) != 0) {
-          error->warning(FLERR, fmt::format("Could not delete {}", nameslist[fileidx]));
+          error->warning(FLERR, "Could not delete {}", nameslist[fileidx]);
         }
         delete[] nameslist[fileidx];
         nameslist[fileidx] = utils::strdup(filecurrent);
diff --git a/src/COMPRESS/dump_local_gz.cpp b/src/COMPRESS/dump_local_gz.cpp
index 9c6c06e65a..6af26fd944 100644
--- a/src/COMPRESS/dump_local_gz.cpp
+++ b/src/COMPRESS/dump_local_gz.cpp
@@ -72,7 +72,7 @@ void DumpLocalGZ::openfile()
         ++numfiles;
       } else {
         if (remove(nameslist[fileidx]) != 0) {
-          error->warning(FLERR, fmt::format("Could not delete {}", nameslist[fileidx]));
+          error->warning(FLERR, "Could not delete {}", nameslist[fileidx]);
         }
         delete[] nameslist[fileidx];
         nameslist[fileidx] = utils::strdup(filecurrent);
diff --git a/src/COMPRESS/dump_local_zstd.cpp b/src/COMPRESS/dump_local_zstd.cpp
index f20dc5016c..ec00800e37 100644
--- a/src/COMPRESS/dump_local_zstd.cpp
+++ b/src/COMPRESS/dump_local_zstd.cpp
@@ -79,7 +79,7 @@ void DumpLocalZstd::openfile()
         ++numfiles;
       } else {
         if (remove(nameslist[fileidx]) != 0) {
-          error->warning(FLERR, fmt::format("Could not delete {}", nameslist[fileidx]));
+          error->warning(FLERR, "Could not delete {}", nameslist[fileidx]);
         }
         delete[] nameslist[fileidx];
         nameslist[fileidx] = utils::strdup(filecurrent);
diff --git a/src/KSPACE/ewald_disp.cpp b/src/KSPACE/ewald_disp.cpp
index 927485ef84..620d371b1f 100644
--- a/src/KSPACE/ewald_disp.cpp
+++ b/src/KSPACE/ewald_disp.cpp
@@ -213,11 +213,10 @@ void EwaldDisp::init()
     error->all(FLERR,"Cannot (yet) use 'electron' units with dipoles");
 
   if (qsqsum == 0.0 && bsbsum == 0.0 && M2 == 0.0)
-      error->all(FLERR,"Cannot use Ewald/disp solver "
-                 "on system with no charge, dipole, or LJ particles");
+      error->all(FLERR,"Cannot use Ewald/disp solver on system without "
+                 "charged, dipole, or LJ particles");
   if (fabs(qsum) > SMALL && comm->me == 0)
-    error->warning(FLERR,fmt::format("System is not charge neutral, "
-                                     "net charge = {:.8g}",qsum));
+    error->warning(FLERR,"System is not charge neutral, net charge = {:.8g}",qsum);
 
   if (!function[1] && !function[2]) dispersionflag = 0;
   if (!function[3]) dipoleflag = 0;
diff --git a/src/KSPACE/msm.cpp b/src/KSPACE/msm.cpp
index 490fbae0e0..bbd4b01a68 100644
--- a/src/KSPACE/msm.cpp
+++ b/src/KSPACE/msm.cpp
@@ -1085,8 +1085,8 @@ void MSM::set_grid_global()
     *p_cutoff = cutoff;
 
     if (me == 0)
-      error->warning(FLERR,fmt::format("Adjusting Coulombic cutoff for "
-                                       "MSM, new cutoff = {:.8}", cutoff));
+      error->warning(FLERR,"Adjusting Coulombic cutoff for "
+                     "MSM, new cutoff = {:.8}", cutoff);
   }
 
   if (triclinic == 0) {
diff --git a/src/KSPACE/pppm_disp.cpp b/src/KSPACE/pppm_disp.cpp
index eba653e7d7..a912cf9a45 100644
--- a/src/KSPACE/pppm_disp.cpp
+++ b/src/KSPACE/pppm_disp.cpp
@@ -1362,8 +1362,8 @@ void PPPMDisp::init_coeffs()
 
       err =  bmax/amax;
       if (err > 1.0e-4 && comm->me == 0)
-        error->warning(FLERR,fmt::format("Estimated error in splitting of "
-                                         "dispersion coeffs is {}",err));
+        error->warning(FLERR,"Estimated error in splitting of "
+                       "dispersion coeffs is {}",err);
       // set B
 
       B = new double[nsplit*n+nsplit];
diff --git a/src/MISC/fix_deposit.cpp b/src/MISC/fix_deposit.cpp
index 7aa7b69ecf..13eef1d2b4 100644
--- a/src/MISC/fix_deposit.cpp
+++ b/src/MISC/fix_deposit.cpp
@@ -287,8 +287,8 @@ void FixDeposit::init()
 
     double separation = MAX(2.0*maxradinsert,maxradall+maxradinsert);
     if (sqrt(nearsq) < separation && comm->me == 0)
-      error->warning(FLERR,fmt::format("Fix deposit near setting < possible "
-                                       "overlap separation {}",separation));
+      error->warning(FLERR,"Fix deposit near setting < possible "
+                     "overlap separation {}",separation);
   }
 }
 
diff --git a/src/MOLECULE/bond_fene.cpp b/src/MOLECULE/bond_fene.cpp
index 4607e6ebb1..a81ad34e69 100644
--- a/src/MOLECULE/bond_fene.cpp
+++ b/src/MOLECULE/bond_fene.cpp
@@ -85,8 +85,8 @@ void BondFENE::compute(int eflag, int vflag)
     // if r > 2*r0 something serious is wrong, abort
 
     if (rlogarg < 0.1) {
-      error->warning(FLERR,fmt::format("FENE bond too long: {} {} {} {}",
-                     update->ntimestep,atom->tag[i1],atom->tag[i2],sqrt(rsq)));
+      error->warning(FLERR,"FENE bond too long: {} {} {} {}",
+                     update->ntimestep,atom->tag[i1],atom->tag[i2],sqrt(rsq));
       if (rlogarg <= -3.0) error->one(FLERR,"Bad FENE bond");
       rlogarg = 0.1;
     }
diff --git a/src/MOLECULE/bond_table.cpp b/src/MOLECULE/bond_table.cpp
index af5eb36bf9..a0bbcdb512 100644
--- a/src/MOLECULE/bond_table.cpp
+++ b/src/MOLECULE/bond_table.cpp
@@ -378,15 +378,15 @@ void BondTable::read_table(Table *tb, char *file, char *keyword)
   }
 
   if (ferror) {
-    error->warning(FLERR, fmt::format("{} of {} force values in table are inconsistent with -dE/dr.\n"
-                                      "  Should only be flagged at inflection points",ferror,tb->ninput));
+    error->warning(FLERR, "{} of {} force values in table are inconsistent with -dE/dr.\n"
+                   "WARNING:  Should only be flagged at inflection points",ferror,tb->ninput);
   }
 
   // warn if data was read incompletely, e.g. columns were missing
 
   if (cerror) {
-    error->warning(FLERR, fmt::format("{} of {} lines in table were incomplete or could not be"
-                                      " parsed completely",cerror,tb->ninput));
+    error->warning(FLERR, "{} of {} lines in table were incomplete or could not be"
+                   " parsed completely",cerror,tb->ninput);
   }
 }
 
diff --git a/src/PLUGIN/plugin.cpp b/src/PLUGIN/plugin.cpp
index 4434b28d16..1650284747 100644
--- a/src/PLUGIN/plugin.cpp
+++ b/src/PLUGIN/plugin.cpp
@@ -171,9 +171,8 @@ namespace LAMMPS_NS
       auto pair_map = lmp->force->pair_map;
       if (pair_map->find(plugin->name) != pair_map->end()) {
         if (lmp->comm->me == 0)
-          lmp->error->warning(FLERR,fmt::format("Overriding built-in pair "
-                                                "style {} from plugin",
-                                                plugin->name));
+          lmp->error->warning(FLERR,"Overriding built-in pair "
+                              "style {} from plugin",plugin->name);
       }
       (*pair_map)[plugin->name] = (Force::PairCreator)plugin->creator.v1;
 
@@ -181,9 +180,8 @@ namespace LAMMPS_NS
       auto bond_map = lmp->force->bond_map;
       if (bond_map->find(plugin->name) != bond_map->end()) {
         if (lmp->comm->me == 0)
-          lmp->error->warning(FLERR,fmt::format("Overriding built-in bond "
-                                                "style {} from plugin",
-                                                plugin->name));
+          lmp->error->warning(FLERR,"Overriding built-in bond "
+                              "style {} from plugin",plugin->name);
       }
       (*bond_map)[plugin->name] = (Force::BondCreator)plugin->creator.v1;
 
@@ -191,9 +189,8 @@ namespace LAMMPS_NS
       auto angle_map = lmp->force->angle_map;
       if (angle_map->find(plugin->name) != angle_map->end()) {
         if (lmp->comm->me == 0)
-          lmp->error->warning(FLERR,fmt::format("Overriding built-in angle "
-                                                "style {} from plugin",
-                                                plugin->name));
+          lmp->error->warning(FLERR,"Overriding built-in angle "
+                              "style {} from plugin",plugin->name);
       }
       (*angle_map)[plugin->name] = (Force::AngleCreator)plugin->creator.v1;
 
@@ -201,9 +198,8 @@ namespace LAMMPS_NS
       auto dihedral_map = lmp->force->dihedral_map;
       if (dihedral_map->find(plugin->name) != dihedral_map->end()) {
         if (lmp->comm->me == 0)
-          lmp->error->warning(FLERR,fmt::format("Overriding built-in dihedral "
-                                                "style {} from plugin",
-                                                plugin->name));
+          lmp->error->warning(FLERR,"Overriding built-in dihedral "
+                              "style {} from plugin",plugin->name);
       }
       (*dihedral_map)[plugin->name] = (Force::DihedralCreator)plugin->creator.v1;
 
@@ -211,9 +207,8 @@ namespace LAMMPS_NS
       auto improper_map = lmp->force->improper_map;
       if (improper_map->find(plugin->name) != improper_map->end()) {
         if (lmp->comm->me == 0)
-          lmp->error->warning(FLERR,fmt::format("Overriding built-in improper "
-                                                "style {} from plugin",
-                                                plugin->name));
+          lmp->error->warning(FLERR,"Overriding built-in improper "
+                              "style {} from plugin",plugin->name);
       }
       (*improper_map)[plugin->name] = (Force::ImproperCreator)plugin->creator.v1;
 
@@ -221,9 +216,8 @@ namespace LAMMPS_NS
       auto compute_map = lmp->modify->compute_map;
       if (compute_map->find(plugin->name) != compute_map->end()) {
         if (lmp->comm->me == 0)
-          lmp->error->warning(FLERR,fmt::format("Overriding built-in compute "
-                                                "style {} from plugin",
-                                                plugin->name));
+          lmp->error->warning(FLERR,"Overriding built-in compute "
+                              "style {} from plugin",plugin->name);
       }
       (*compute_map)[plugin->name] = (Modify::ComputeCreator)plugin->creator.v2;
 
@@ -231,9 +225,8 @@ namespace LAMMPS_NS
       auto fix_map = lmp->modify->fix_map;
       if (fix_map->find(plugin->name) != fix_map->end()) {
         if (lmp->comm->me == 0)
-          lmp->error->warning(FLERR,fmt::format("Overriding built-in fix "
-                                                "style {} from plugin",
-                                                plugin->name));
+          lmp->error->warning(FLERR,"Overriding built-in fix "
+                              "style {} from plugin",plugin->name);
       }
       (*fix_map)[plugin->name] = (Modify::FixCreator)plugin->creator.v2;
 
@@ -241,9 +234,8 @@ namespace LAMMPS_NS
       auto region_map = lmp->domain->region_map;
       if (region_map->find(plugin->name) != region_map->end()) {
         if (lmp->comm->me == 0)
-          lmp->error->warning(FLERR,fmt::format("Overriding built-in region "
-                                                "style {} from plugin",
-                                                plugin->name));
+          lmp->error->warning(FLERR,"Overriding built-in region "
+                              "style {} from plugin",plugin->name);
       }
       (*region_map)[plugin->name] = (Domain::RegionCreator)plugin->creator.v2;
 
@@ -251,9 +243,8 @@ namespace LAMMPS_NS
       auto command_map = lmp->input->command_map;
       if (command_map->find(plugin->name) != command_map->end()) {
         if (lmp->comm->me == 0)
-          lmp->error->warning(FLERR,fmt::format("Overriding built-in command "
-                                                "style {} from plugin",
-                                                plugin->name));
+          lmp->error->warning(FLERR,"Overriding built-in command "
+                              "style {} from plugin",plugin->name);
       }
       (*command_map)[plugin->name] = (Input::CommandCreator)plugin->creator.v1;
 
diff --git a/src/QEQ/fix_qeq.cpp b/src/QEQ/fix_qeq.cpp
index fe6948c6a0..bca2914b82 100644
--- a/src/QEQ/fix_qeq.cpp
+++ b/src/QEQ/fix_qeq.cpp
@@ -387,10 +387,9 @@ int FixQEq::CG( double *b, double *x )
   }
 
   if ((comm->me == 0) && (loop >= maxiter))
-    error->warning(FLERR,fmt::format("Fix qeq CG convergence failed ({}) "
-                                     "after {} iterations at step {}",
-                                     sqrt(sig_new)/b_norm,loop,
-                                     update->ntimestep));
+    error->warning(FLERR,"Fix qeq CG convergence failed ({}) after {} "
+                   "iterations at step {}",sqrt(sig_new)/b_norm,loop,
+                   update->ntimestep);
   return loop;
 }
 
diff --git a/src/QEQ/fix_qeq_dynamic.cpp b/src/QEQ/fix_qeq_dynamic.cpp
index 397393b786..84ad081cdc 100644
--- a/src/QEQ/fix_qeq_dynamic.cpp
+++ b/src/QEQ/fix_qeq_dynamic.cpp
@@ -155,8 +155,8 @@ void FixQEqDynamic::pre_force(int /*vflag*/)
   }
 
   if ((comm->me == 0) && (iloop >= maxiter))
-      error->warning(FLERR,fmt::format("Charges did not converge at step "
-                                       "{}: {}",update->ntimestep,enegchk));
+      error->warning(FLERR,"Charges did not converge at step {}: {}",
+                     update->ntimestep,enegchk);
 
   if (force->kspace) force->kspace->qsum_qsq();
 }
diff --git a/src/QEQ/fix_qeq_fire.cpp b/src/QEQ/fix_qeq_fire.cpp
index 0bdf65dc18..3860e775d4 100644
--- a/src/QEQ/fix_qeq_fire.cpp
+++ b/src/QEQ/fix_qeq_fire.cpp
@@ -215,8 +215,8 @@ void FixQEqFire::pre_force(int /*vflag*/)
   }
 
   if ((comm->me == 0) && (iloop >= maxiter))
-    error->warning(FLERR,fmt::format("Charges did not converge at step "
-                                     "{}: {}",update->ntimestep,enegchk));
+    error->warning(FLERR,"Charges did not converge at step {}: {}",
+                   update->ntimestep,enegchk);
 
   if (force->kspace) force->kspace->qsum_qsq();
 }
diff --git a/src/RIGID/fix_rigid.cpp b/src/RIGID/fix_rigid.cpp
index e8f251856d..24ce241670 100644
--- a/src/RIGID/fix_rigid.cpp
+++ b/src/RIGID/fix_rigid.cpp
@@ -697,8 +697,8 @@ void FixRigid::init()
       if (modify->fix[i]->rigid_flag) rflag = 1;
       if (rflag && (modify->fmask[i] & POST_FORCE) &&
           !modify->fix[i]->rigid_flag)
-        error->warning(FLERR,fmt::format("Fix {} alters forces after fix "
-                                         "rigid",modify->fix[i]->id));
+        error->warning(FLERR,"Fix {} alters forces after fix rigid",
+                       modify->fix[i]->id);
     }
   }
 
diff --git a/src/RIGID/fix_rigid_small.cpp b/src/RIGID/fix_rigid_small.cpp
index 05856dc3fa..60348fb5ce 100644
--- a/src/RIGID/fix_rigid_small.cpp
+++ b/src/RIGID/fix_rigid_small.cpp
@@ -548,8 +548,8 @@ void FixRigidSmall::init()
       if (modify->fix[i]->rigid_flag) rflag = 1;
       if (rflag && (modify->fmask[i] & POST_FORCE) &&
           !modify->fix[i]->rigid_flag)
-        error->warning(FLERR,fmt::format("Fix {} alters forces after fix "
-                                         "rigid",modify->fix[i]->id));
+        error->warning(FLERR,"Fix {} alters forces after fix rigid",
+                       modify->fix[i]->id);
     }
   }
 
diff --git a/src/USER-BOCS/fix_bocs.cpp b/src/USER-BOCS/fix_bocs.cpp
index 20c2a9dfe8..da0ea3658b 100644
--- a/src/USER-BOCS/fix_bocs.cpp
+++ b/src/USER-BOCS/fix_bocs.cpp
@@ -629,7 +629,7 @@ int FixBocs::read_F_table( char *filename, int p_basis_type )
     // NB: LAMMPS coding guidelines prefer cstdio so we are intentionally
     // foregoing  reading with getline
     if (comm->me == 0) {
-        error->message(FLERR, fmt::format("INFO: About to read data file: {}", filename));
+        error->message(FLERR, "INFO: About to read data file: {}", filename);
     }
 
     // Data file lines hold two floating point numbers.
@@ -645,7 +645,7 @@ int FixBocs::read_F_table( char *filename, int p_basis_type )
 
     numEntries = inputLines.size();
     if (comm->me == 0) {
-      error->message(FLERR, fmt::format("INFO: Read {} lines from file", numEntries));
+      error->message(FLERR, "INFO: Read {} lines from file", numEntries);
     }
 
 
@@ -670,34 +670,23 @@ int FixBocs::read_F_table( char *filename, int p_basis_type )
       test_sscanf = sscanf(inputLines.at(i).c_str()," %f , %f ",&f1, &f2);
       if (test_sscanf == 2)
       {
-        //if (comm->me == 0) {
-        //    error->message(FLERR, fmt::format("INFO: f1 = {}, f2 = {}", f1, f2));
-        //}
         data[VOLUME][i] = (double)f1;
         data[PRESSURE_CORRECTION][i] = (double)f2;
         if (i == 1)
         {
           // second entry is used to compute the validation interval used below
           stdVolumeInterval = data[VOLUME][i] - data[VOLUME][i-1];
-          //if (comm->me == 0) {
-          //    error->message(FLERR, fmt::format("INFO: standard volume interval computed: {}", stdVolumeInterval));
-          //}
         }
         else if (i > 1)
         {
           // after second entry, all intervals are validated
           currVolumeInterval = data[VOLUME][i] - data[VOLUME][i-1];
-          //if (comm->me == 0) {
-          //    error->message(FLERR, fmt::format("INFO: current volume interval: {}", currVolumeInterval));
-          //}
           if (fabs(currVolumeInterval - stdVolumeInterval) > volumeIntervalTolerance) {
-            if (comm->me == 0) {
-                message = fmt::format("Bad volume interval. Spline analysis requires uniform"
-                                      " volume distribution, found inconsistent volume"
-                                      " differential, line {} of file {}\n\tline: {}",
-                                      lineNum, filename, inputLines.at(i));
-                error->warning(FLERR, message);
-            }
+            if (comm->me == 0)
+              error->warning(FLERR,"Bad volume interval. Spline analysis requires uniform"
+                             " volume distribution, found inconsistent volume"
+                             " differential, line {} of file {}\nWARNING:\tline: {}",
+                             lineNum, filename, inputLines.at(i));
             badInput = true;
             numBadVolumeIntervals++;
           }
@@ -706,12 +695,10 @@ int FixBocs::read_F_table( char *filename, int p_basis_type )
       }
       else
       {
-        if (comm->me == 0) {
-          message = fmt::format("Bad input format: did not find 2 comma separated numeric"
-                                " values in line {} of file {}\n\tline: {}",
-                                lineNum, filename, inputLines.at(i));
-          error->warning(FLERR, message);
-        }
+        if (comm->me == 0)
+          error->warning(FLERR,"Bad input format: did not find 2 comma separated numeric"
+                         " values in line {} of file {}\nWARNING:\tline: {}",
+                         lineNum, filename, inputLines.at(i));
         badInput = true;
       }
       if (badInput)
@@ -721,7 +708,7 @@ int FixBocs::read_F_table( char *filename, int p_basis_type )
     }
 
     if (numBadVolumeIntervals > 0 && comm->me == 0) {
-      error->message(FLERR, fmt::format("INFO: total number bad volume intervals = {}", numBadVolumeIntervals));
+      error->message(FLERR, "INFO: total number bad volume intervals = {}", numBadVolumeIntervals);
     }
   }
   else {
@@ -729,7 +716,7 @@ int FixBocs::read_F_table( char *filename, int p_basis_type )
   }
 
   if (badInput && comm->me == 0) {
-    error->warning(FLERR,fmt::format("Bad volume / pressure-correction data: {}\nSee details above", filename));
+    error->warning(FLERR,"Bad volume / pressure-correction data: {}\nSee details above", filename);
   }
 
   if (p_basis_type == BASIS_LINEAR_SPLINE)
@@ -752,9 +739,6 @@ int FixBocs::read_F_table( char *filename, int p_basis_type )
 }
 
 int FixBocs::build_linear_splines(double **data) {
-  //if (comm->me == 0) {
-    //error->message(FLERR, fmt::format("INFO: entering build_linear_splines, spline_length = {}", spline_length));
-  //}
   splines = (double **) calloc(NUM_LINEAR_SPLINE_COLUMNS,sizeof(double *));
   splines[VOLUME] = (double *) calloc(spline_length,sizeof(double));
   splines[PRESSURE_CORRECTION] = (double *) calloc(spline_length,sizeof(double));
@@ -766,7 +750,7 @@ int FixBocs::build_linear_splines(double **data) {
   }
 
   if (comm->me == 0) {
-    error->message(FLERR, fmt::format("INFO: leaving build_linear_splines, spline_length = {}", spline_length));
+    error->message(FLERR, "INFO: leaving build_linear_splines, spline_length = {}", spline_length);
   }
 
   return spline_length;
@@ -774,9 +758,6 @@ int FixBocs::build_linear_splines(double **data) {
 
 int FixBocs::build_cubic_splines(double **data)
 {
-  //if (comm->me == 0) {
-    //error->message(FLERR, fmt::format("INFO: entering build_cubic_splines, spline_length = {}", spline_length));
-  //}
   int n = spline_length;
   double *a, *b, *d, *h, *alpha, *c, *l, *mu, *z;
   // 2020-07-17 ag:
@@ -867,7 +848,7 @@ int FixBocs::build_cubic_splines(double **data)
   memory->destroy(z);
 
   if (comm->me == 0) {
-    error->message(FLERR, fmt::format("INFO: leaving build_cubic_splines, numSplines = {}", numSplines));
+    error->message(FLERR, "INFO: leaving build_cubic_splines, numSplines = {}", numSplines);
   }
 
   // Tell the caller how many splines we created
diff --git a/src/USER-MESONT/pair_mesocnt.cpp b/src/USER-MESONT/pair_mesocnt.cpp
index 3a56c69d2d..cff99395ff 100644
--- a/src/USER-MESONT/pair_mesocnt.cpp
+++ b/src/USER-MESONT/pair_mesocnt.cpp
@@ -920,20 +920,17 @@ void PairMesoCNT::read_data(FILE *fp, double **data,
   // warn if data was read incompletely, e.g. columns were missing
 
   if (cerror)
-    error->warning(FLERR,fmt::format("{} of {} lines were incomplete or could "
-                                     "not be parsed completely in pair table: {}",
-                                     cerror,ninput*ninput,file));
+    error->warning(FLERR,"{} of {} lines were incomplete or could not be parsed "
+                   "completely in pair table: {}",cerror,ninput*ninput,file);
 
   // warn if spacing between data points is not constant
 
   if (sxerror)
-    error->warning(FLERR,fmt::format("{} spacings in first column were different "
-                                     " from first spacing in pair table: {}",
-                                     sxerror,file));
+    error->warning(FLERR,"{} spacings in first column were different from "
+                   "first spacing in pair table: {}",sxerror,file);
   if (syerror)
-    error->warning(FLERR,fmt::format("{} spacings in second column were different "
-                                     " from first spacing in pair table: {}",
-                                     syerror,file));
+    error->warning(FLERR,"{} spacings in second column were different from "
+                   "first spacing in pair table: {}",syerror,file);
 }
 
 /* ----------------------------------------------------------------------
diff --git a/src/USER-MISC/pair_agni.cpp b/src/USER-MISC/pair_agni.cpp
index 7acaf90e4f..ec5cfaad06 100644
--- a/src/USER-MISC/pair_agni.cpp
+++ b/src/USER-MISC/pair_agni.cpp
@@ -349,8 +349,7 @@ void PairAGNI::read_file(char *filename)
               params[curparam].gwidth = 0.0;
             wantdata = curparam;
             curparam = -1;
-          } else error->warning(FLERR,fmt::format("Ignoring unknown tag '{}' "
-                                                  "in AGNI potential file.",tag));
+          } else error->warning(FLERR,"Ignoring unknown tag '{}' in AGNI potential file.",tag);
         } else {
           if (params && wantdata >=0) {
             if ((int)values.count() == params[wantdata].numeta + 2) {
diff --git a/src/change_box.cpp b/src/change_box.cpp
index 78f1261caf..d57ce3e640 100644
--- a/src/change_box.cpp
+++ b/src/change_box.cpp
@@ -389,9 +389,8 @@ void ChangeBox::command(int narg, char **arg)
   bigint nblocal = atom->nlocal;
   MPI_Allreduce(&nblocal,&natoms,1,MPI_LMP_BIGINT,MPI_SUM,world);
   if (natoms != atom->natoms && comm->me == 0)
-    error->warning(FLERR,fmt::format("Lost atoms via change_box: "
-                                     "original {} current {}",
-                                     atom->natoms,natoms));
+    error->warning(FLERR,"Lost atoms via change_box: original {} "
+                   "current {}", atom->natoms,natoms);
 }
 
 /* ----------------------------------------------------------------------
diff --git a/src/comm.cpp b/src/comm.cpp
index 50d20ac7bb..ec56bbe28d 100644
--- a/src/comm.cpp
+++ b/src/comm.cpp
@@ -655,18 +655,16 @@ double Comm::get_comm_cutoff()
     maxcommcutoff = MAX(maxcommcutoff,maxbondcutoff);
   } else {
     if ((me == 0) && (maxbondcutoff > maxcommcutoff))
-      error->warning(FLERR,fmt::format("Communication cutoff {} is shorter "
-                                       "than a bond length based estimate of "
-                                       "{}. This may lead to errors.",
-                                       maxcommcutoff,maxbondcutoff));
+      error->warning(FLERR,"Communication cutoff {} is shorter than a bond "
+                     "length based estimate of {}. This may lead to errors.",
+                     maxcommcutoff,maxbondcutoff);
   }
 
   // print warning if neighborlist cutoff overrides user cutoff
 
   if ((me == 0) && (update->setupflag == 1)) {
     if ((cutghostuser > 0.0) && (maxcommcutoff > cutghostuser))
-      error->warning(FLERR,fmt::format("Communication cutoff adjusted to {}",
-                                       maxcommcutoff));
+      error->warning(FLERR,"Communication cutoff adjusted to {}",maxcommcutoff);
   }
 
   return maxcommcutoff;
diff --git a/src/compute_cna_atom.cpp b/src/compute_cna_atom.cpp
index 5288504a4f..318450e2b7 100644
--- a/src/compute_cna_atom.cpp
+++ b/src/compute_cna_atom.cpp
@@ -186,8 +186,7 @@ void ComputeCNAAtom::compute_peratom()
   int nerrorall;
   MPI_Allreduce(&nerror,&nerrorall,1,MPI_INT,MPI_SUM,world);
   if (nerrorall && comm->me == 0)
-    error->warning(FLERR,fmt::format("Too many neighbors in CNA for {} "
-                                     "atoms",nerrorall));
+    error->warning(FLERR,"Too many neighbors in CNA for {} atoms",nerrorall);
 
   // compute CNA for each atom in group
   // only performed if # of nearest neighbors = 12 or 14 (fcc,hcp)
@@ -345,8 +344,7 @@ void ComputeCNAAtom::compute_peratom()
 
   MPI_Allreduce(&nerror,&nerrorall,1,MPI_INT,MPI_SUM,world);
   if (nerrorall && comm->me == 0)
-    error->warning(FLERR,fmt::format("Too many common neighbors in CNA {} "
-                                     "times", nerrorall));
+    error->warning(FLERR,"Too many common neighbors in CNA: {}x", nerrorall);
 }
 
 /* ----------------------------------------------------------------------
diff --git a/src/displace_atoms.cpp b/src/displace_atoms.cpp
index 6bc3b0ab35..a8d55b8011 100644
--- a/src/displace_atoms.cpp
+++ b/src/displace_atoms.cpp
@@ -354,9 +354,8 @@ void DisplaceAtoms::command(int narg, char **arg)
   bigint nblocal = atom->nlocal;
   MPI_Allreduce(&nblocal,&natoms,1,MPI_LMP_BIGINT,MPI_SUM,world);
   if (natoms != atom->natoms && comm->me == 0)
-    error->warning(FLERR,fmt::format("Lost atoms via displace_atoms: "
-                                     "original {} current {}",
-                                     atom->natoms,natoms));
+    error->warning(FLERR,"Lost atoms via displace_atoms: original {} "
+                   "current {}",atom->natoms,natoms);
 }
 
 /* ----------------------------------------------------------------------
diff --git a/src/error.cpp b/src/error.cpp
index 5d9061b7ce..660acf775b 100644
--- a/src/error.cpp
+++ b/src/error.cpp
@@ -258,6 +258,20 @@ void Error::warning(const std::string &file, int line, const std::string &str)
   if (logfile) fputs(mesg.c_str(),logfile);
 }
 
+/* ----------------------------------------------------------------------
+   forward vararg version to single string version
+------------------------------------------------------------------------- */
+
+void Error::_warning(const std::string &file, int line, fmt::string_view format,
+                     fmt::format_args args)
+{
+  try {
+    warning(file,line,fmt::vformat(format, args));
+  } catch (fmt::format_error &e) {
+    warning(file,line,e.what());
+  }
+}
+
 /* ----------------------------------------------------------------------
    called by one proc in world, typically proc 0
    write message to screen and logfile (if logflag is set)
@@ -271,6 +285,20 @@ void Error::message(const std::string &file, int line, const std::string &str)
   if (logfile) fputs(mesg.c_str(),logfile);
 }
 
+/* ----------------------------------------------------------------------
+   forward vararg version to single string version
+------------------------------------------------------------------------- */
+
+void Error::_message(const std::string &file, int line, fmt::string_view format,
+                     fmt::format_args args)
+{
+  try {
+    message(file,line,fmt::vformat(format, args));
+  } catch (fmt::format_error &e) {
+    message(file,line,e.what());
+  }
+}
+
 /* ----------------------------------------------------------------------
    shutdown LAMMPS
    called by all procs in one world
diff --git a/src/error.h b/src/error.h
index c39f5d07c9..fb82b05b34 100644
--- a/src/error.h
+++ b/src/error.h
@@ -31,12 +31,13 @@ class Error : protected Pointers {
   void universe_warn(const std::string &, int, const std::string &);
 
   [[ noreturn ]] void all(const std::string &, int, const std::string &);
-  [[ noreturn ]] void one(const std::string &, int, const std::string &);
   template <typename S, typename... Args>
   void all(const std::string &file, int line, const S &format,
                           Args&&... args) {
     _all(file, line, format, fmt::make_args_checked<Args...>(format, args...));
   }
+
+  [[ noreturn ]] void one(const std::string &, int, const std::string &);
   template <typename S, typename... Args>
   void one(const std::string &file, int line, const S &format,
                           Args&&... args) {
@@ -44,7 +45,16 @@ class Error : protected Pointers {
   }
 
   void warning(const std::string &, int, const std::string &);
+  template <typename S, typename... Args>
+  void warning(const std::string &file, int line, const S &format, Args&&... args) {
+    _warning(file, line, format, fmt::make_args_checked<Args...>(format, args...));
+  }
+
   void message(const std::string &, int, const std::string &);
+  template <typename S, typename... Args>
+  void message(const std::string &file, int line, const S &format, Args&&... args) {
+    _message(file, line, format, fmt::make_args_checked<Args...>(format, args...));
+  }
   [[ noreturn ]] void done(int = 0); // 1 would be fully backwards compatible
 
   int get_numwarn() const { return numwarn; }
@@ -70,6 +80,8 @@ class Error : protected Pointers {
                            fmt::format_args args);
   [[ noreturn ]] void _one(const std::string &, int, fmt::string_view,
                            fmt::format_args args);
+  void _warning(const std::string &, int, fmt::string_view, fmt::format_args args);
+  void _message(const std::string &, int, fmt::string_view, fmt::format_args args);
 };
 
 }
diff --git a/src/kspace.cpp b/src/kspace.cpp
index f44cc42aaf..fa7e68d90e 100644
--- a/src/kspace.cpp
+++ b/src/kspace.cpp
@@ -336,7 +336,7 @@ double KSpace::estimate_table_accuracy(double q2_over_sqrt, double spr)
   int nctb = force->pair->ncoultablebits;
   if (comm->me == 0) {
     if (nctb)
-      error->message(FLERR,fmt::format("  using {}-bit tables for long-range coulomb",nctb));
+      error->message(FLERR,"  using {}-bit tables for long-range coulomb",nctb);
     else
       error->message(FLERR,"  using polynomial approximation for long-range coulomb");
   }
diff --git a/src/ntopo_angle_all.cpp b/src/ntopo_angle_all.cpp
index b7811052df..c8187c0469 100644
--- a/src/ntopo_angle_all.cpp
+++ b/src/ntopo_angle_all.cpp
@@ -88,6 +88,5 @@ void NTopoAngleAll::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && (me == 0))
-    error->warning(FLERR,fmt::format("Angle atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Angle atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/ntopo_angle_partial.cpp b/src/ntopo_angle_partial.cpp
index 543658f19f..1dea896758 100644
--- a/src/ntopo_angle_partial.cpp
+++ b/src/ntopo_angle_partial.cpp
@@ -89,6 +89,5 @@ void NTopoAnglePartial::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && (me == 0))
-    error->warning(FLERR,fmt::format("Angle atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Angle atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/ntopo_angle_template.cpp b/src/ntopo_angle_template.cpp
index ad09979a7a..ede8c398dc 100644
--- a/src/ntopo_angle_template.cpp
+++ b/src/ntopo_angle_template.cpp
@@ -109,6 +109,5 @@ void NTopoAngleTemplate::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && (me == 0))
-    error->warning(FLERR,fmt::format("Angle atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Angle atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/ntopo_bond_all.cpp b/src/ntopo_bond_all.cpp
index 578f98ec81..02d44f090c 100644
--- a/src/ntopo_bond_all.cpp
+++ b/src/ntopo_bond_all.cpp
@@ -81,6 +81,5 @@ void NTopoBondAll::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && (me == 0))
-    error->warning(FLERR,fmt::format("Bond atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Bond atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/ntopo_bond_partial.cpp b/src/ntopo_bond_partial.cpp
index 8d077106db..c5afe08630 100644
--- a/src/ntopo_bond_partial.cpp
+++ b/src/ntopo_bond_partial.cpp
@@ -82,6 +82,5 @@ void NTopoBondPartial::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && (me == 0))
-    error->warning(FLERR,fmt::format("Bond atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Bond atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/ntopo_bond_template.cpp b/src/ntopo_bond_template.cpp
index 887ac3aa81..45297fc92c 100644
--- a/src/ntopo_bond_template.cpp
+++ b/src/ntopo_bond_template.cpp
@@ -100,6 +100,5 @@ void NTopoBondTemplate::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && (me == 0))
-    error->warning(FLERR,fmt::format("Bond atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Bond atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/ntopo_dihedral_all.cpp b/src/ntopo_dihedral_all.cpp
index b77e0cc33f..cbe2e46e5c 100644
--- a/src/ntopo_dihedral_all.cpp
+++ b/src/ntopo_dihedral_all.cpp
@@ -94,6 +94,5 @@ void NTopoDihedralAll::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && (me == 0))
-    error->warning(FLERR,fmt::format("Dihedral atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Dihedral atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/ntopo_dihedral_partial.cpp b/src/ntopo_dihedral_partial.cpp
index 980f073b67..c8a1f22100 100644
--- a/src/ntopo_dihedral_partial.cpp
+++ b/src/ntopo_dihedral_partial.cpp
@@ -96,6 +96,5 @@ void NTopoDihedralPartial::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && (me == 0))
-    error->warning(FLERR,fmt::format("Dihedral atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Dihedral atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/ntopo_dihedral_template.cpp b/src/ntopo_dihedral_template.cpp
index 5c6f3d333f..564e7aca69 100644
--- a/src/ntopo_dihedral_template.cpp
+++ b/src/ntopo_dihedral_template.cpp
@@ -115,6 +115,5 @@ void NTopoDihedralTemplate::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && (me == 0))
-    error->warning(FLERR,fmt::format("Dihedral atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Dihedral atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/ntopo_improper_all.cpp b/src/ntopo_improper_all.cpp
index 936ed279d7..52f323b735 100644
--- a/src/ntopo_improper_all.cpp
+++ b/src/ntopo_improper_all.cpp
@@ -94,6 +94,5 @@ void NTopoImproperAll::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && (me == 0))
-    error->warning(FLERR,fmt::format("Improper atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Improper atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/ntopo_improper_partial.cpp b/src/ntopo_improper_partial.cpp
index 911e968326..76d31061b7 100644
--- a/src/ntopo_improper_partial.cpp
+++ b/src/ntopo_improper_partial.cpp
@@ -98,6 +98,5 @@ void NTopoImproperPartial::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && me == 0)
-    error->warning(FLERR,fmt::format("Improper atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Improper atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/ntopo_improper_template.cpp b/src/ntopo_improper_template.cpp
index 68cbebd40e..7fd2f3352e 100644
--- a/src/ntopo_improper_template.cpp
+++ b/src/ntopo_improper_template.cpp
@@ -115,6 +115,5 @@ void NTopoImproperTemplate::build()
   int all;
   MPI_Allreduce(&nmissing,&all,1,MPI_INT,MPI_SUM,world);
   if (all && (me == 0))
-    error->warning(FLERR,fmt::format("Improper atoms missing at step {}",
-                                     update->ntimestep));
+    error->warning(FLERR,"Improper atoms missing at step {}",update->ntimestep);
 }
diff --git a/src/pair_table.cpp b/src/pair_table.cpp
index 3c9b51e3f2..17bd222ca0 100644
--- a/src/pair_table.cpp
+++ b/src/pair_table.cpp
@@ -458,25 +458,23 @@ void PairTable::read_table(Table *tb, char *file, char *keyword)
   }
 
   if (ferror)
-    error->warning(FLERR,fmt::format("{} of {} force values in table {} are "
-                                     "inconsistent with -dE/dr.\n  Should "
-                                     "only be flagged at inflection points",
-                                     ferror,tb->ninput,keyword));
+    error->warning(FLERR,"{} of {} force values in table {} are inconsistent "
+                   "with -dE/dr.\nWARNING:  Should only be flagged at "
+                   "inflection points",ferror,tb->ninput,keyword);
 
   // warn if re-computed distance values differ from file values
 
   if (rerror)
-    error->warning(FLERR,fmt::format("{} of {} distance values in table {} "
-                                     "with relative error\n  over {} to "
-                                     "re-computed values",
-                                     rerror,tb->ninput,EPSILONR,keyword));
+    error->warning(FLERR,"{} of {} distance values in table {} with relative "
+                   "error\nWARNING:  over {} to re-computed values",
+                   rerror,tb->ninput,EPSILONR,keyword);
 
   // warn if data was read incompletely, e.g. columns were missing
 
   if (cerror)
-    error->warning(FLERR,fmt::format("{} of {} lines in table {} were "
-                                     "incomplete\n  or could not be parsed "
-                                     "completely",cerror,tb->ninput,keyword));
+    error->warning(FLERR,"{} of {} lines in table {} were incomplete\n"
+                   "WARNING:  or could not be parsed completely",
+                   cerror,tb->ninput,keyword);
 }
 
 /* ----------------------------------------------------------------------
diff --git a/src/potential_file_reader.cpp b/src/potential_file_reader.cpp
index 3d357771c7..a299eb32fc 100644
--- a/src/potential_file_reader.cpp
+++ b/src/potential_file_reader.cpp
@@ -275,8 +275,8 @@ TextFileReader *PotentialFileReader::open_potential(const std::string &path) {
       }
     }
     if (unit_convert != utils::NOCONVERT)
-      lmp->error->warning(FLERR, fmt::format("Converting {} in {} units to {} "
-                                             "units", filetype, units, unit_style));
+      lmp->error->warning(FLERR, "Converting {} in {} units to {} units",
+                          filetype, units, unit_style);
     return new TextFileReader(filepath, filetype);
   }
   return nullptr;
diff --git a/src/read_restart.cpp b/src/read_restart.cpp
index 7edc0bc006..8518aca724 100644
--- a/src/read_restart.cpp
+++ b/src/read_restart.cpp
@@ -694,9 +694,8 @@ void ReadRestart::header()
     } else if (flag == NPROCS) {
       nprocs_file = read_int();
       if (nprocs_file != comm->nprocs && me == 0)
-        error->warning(FLERR,fmt::format("Restart file used different # of "
-                                         "processors: {} vs. {}",nprocs_file,
-                                         comm->nprocs));
+        error->warning(FLERR,"Restart file used different # of processors: "
+                       "{} vs. {}",nprocs_file,comm->nprocs);
 
     // don't set procgrid, warn if different
 
diff --git a/src/thermo.cpp b/src/thermo.cpp
index ce448efdc5..9a543446a9 100644
--- a/src/thermo.cpp
+++ b/src/thermo.cpp
@@ -419,9 +419,8 @@ bigint Thermo::lost_check()
   if ((maxwarn > 0) && (warnbefore == 0) && (ntotal[1] > maxwarn)) {
     warnbefore = 1;
     if (comm->me == 0)
-      error->message(FLERR,fmt::format("WARNING: Too many warnings: {} vs {}. All "
-                                       "future warnings will be suppressed",
-                                       ntotal[1],maxwarn));
+      error->message(FLERR,"WARNING: Too many warnings: {} vs {}. All "
+                     "future warnings will be suppressed",ntotal[1],maxwarn);
   }
   error->set_allwarn(ntotal[1]);
 
@@ -438,13 +437,13 @@ bigint Thermo::lost_check()
 
   if (lostflag == Thermo::ERROR)
     error->all(FLERR,"Lost atoms: original {} current {}",
-                                 atom->natoms,ntotal[0]);
+               atom->natoms,ntotal[0]);
 
   // warning message
 
   if (me == 0)
-    error->warning(FLERR,fmt::format("Lost atoms: original {} current {}",
-                                     atom->natoms,ntotal[0]));
+    error->warning(FLERR,"Lost atoms: original {} current {}",
+                   atom->natoms,ntotal[0]);
 
   // reset total atom count
 
diff --git a/src/update.cpp b/src/update.cpp
index 1f78e48bb3..542e272cb3 100644
--- a/src/update.cpp
+++ b/src/update.cpp
@@ -305,9 +305,8 @@ void Update::set_units(const char *style)
 
   // check if timestep was changed from default value
   if (!dt_default && (comm->me == 0)) {
-    error->warning(FLERR,fmt::format("Changing timestep from {:.6} to {:.6} "
-                                     "due to changing units to {}",
-                                     dt_old, dt, unit_style));
+    error->warning(FLERR,"Changing timestep from {:.6} to {:.6} due to "
+                   "changing units to {}", dt_old, dt, unit_style);
   }
   dt_default = 1;
 }
diff --git a/src/utils.cpp b/src/utils.cpp
index edb9e0e4da..dc9ee453db 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -1200,16 +1200,14 @@ FILE *utils::open_potential(const std::string &name, LAMMPS *lmp,
             && (*auto_convert & REAL2METAL)) {
           *auto_convert = REAL2METAL;
         } else {
-          error->one(FLERR, "Potential file {} requires {} units "
-                                        "but {} units are in use", name,
-                                        units, unit_style);
+          error->one(FLERR, "Potential file {} requires {} units but {} units "
+                     "are in use", name, units, unit_style);
           return nullptr;
         }
       }
       if ((*auto_convert != NOCONVERT) && (me == 0))
-        error->warning(FLERR, fmt::format("Converting potential file in "
-                                          "{} units to {} units",
-                                          units, unit_style));
+        error->warning(FLERR, "Converting potential file in {} units to {} "
+                       "units", units, unit_style);
     }
     return fopen(filepath.c_str(), "r");
   }