diff --git a/src/ELECTRODE/fix_electrode_conp.cpp b/src/ELECTRODE/fix_electrode_conp.cpp
index 412a34a656..ff61eef30e 100644
--- a/src/ELECTRODE/fix_electrode_conp.cpp
+++ b/src/ELECTRODE/fix_electrode_conp.cpp
@@ -124,7 +124,7 @@ FixElectrodeConp::FixElectrodeConp(LAMMPS *lmp, int narg, char **arg) :
     if ((strcmp(arg[iarg], "couple") == 0)) {
       if (iarg + 3 > narg) error->all(FLERR, "Need two arguments after couple keyword");
       int id = group->find(arg[++iarg]);
-      if (id < 0) error->all(FLERR, "Group does not exist");
+      if (id < 0) error->all(FLERR, "Group {} does not exist", arg[iarg]);
       groups.push_back(id);
       group_bits.push_back(group->bitmask[id]);
       ++iarg;
@@ -140,7 +140,7 @@ FixElectrodeConp::FixElectrodeConp(LAMMPS *lmp, int narg, char **arg) :
         group_psi.push_back(utils::numeric(FLERR, arg[iarg], false, lmp));
       }
     } else if ((strcmp(arg[iarg], "algo") == 0)) {
-      if (!default_algo) error->one(FLERR, fmt::format("Algorithm can be set once, only"));
+      if (!default_algo) error->one(FLERR, "Algorithm can be set only once");
       default_algo = false;
       if (iarg + 2 > narg) error->all(FLERR, "Need one argument after algo command");
       char *algo_arg = arg[++iarg];
@@ -157,7 +157,7 @@ FixElectrodeConp::FixElectrodeConp(LAMMPS *lmp, int narg, char **arg) :
         matrix_algo = false;
         cg_algo = true;
       } else {
-        error->all(FLERR, "Invalid argument after algo keyword");
+        error->all(FLERR, "Unknown algo keyword {}", algo_arg);
       }
       if (cg_algo) {
         if (iarg + 2 > narg) error->all(FLERR, "Need one argument after algo *cg command");
@@ -175,7 +175,7 @@ FixElectrodeConp::FixElectrodeConp(LAMMPS *lmp, int narg, char **arg) :
         write_vec = true;
         output_file_vec = arg[++iarg];
       } else {
-        error->all(FLERR, "Illegal fix electrode/conp command with write");
+        error->all(FLERR, "Illegal fix {} command with write", style);
       }
     } else if ((strncmp(arg[iarg], "read", 4) == 0)) {
       if (iarg + 2 > narg) error->all(FLERR, "Need one argument after read command");
@@ -186,12 +186,12 @@ FixElectrodeConp::FixElectrodeConp(LAMMPS *lmp, int narg, char **arg) :
         read_mat = true;
         input_file_mat = arg[++iarg];
       } else {
-        error->all(FLERR, "Illegal fix electrode/conp command with read");
+        error->all(FLERR, "Illegal fix {} command with read", style);
       }
     } else if ((strcmp(arg[iarg], "temp") == 0)) {
       if (iarg + 4 > narg) error->all(FLERR, "Need three arguments after temp command");
-      if (strcmp(this->style, "electrode/thermo") != 0)
-        error->all(FLERR, "temp keyword not available for this electrode fix");
+      if (!utils::strmatch(style, "electrode/thermo"))
+        error->all(FLERR, "temp keyword not available for fix {}", style);
       thermo_temp = force->boltz / force->qe2f * utils::numeric(FLERR, arg[++iarg], false, lmp);
       thermo_time = utils::numeric(FLERR, arg[++iarg], false, lmp);
       thermo_init = utils::inumeric(FLERR, arg[++iarg], false, lmp);
@@ -203,7 +203,7 @@ FixElectrodeConp::FixElectrodeConp(LAMMPS *lmp, int narg, char **arg) :
     } else if ((strcmp(arg[iarg], "ffield") == 0)) {
       ffield = utils::logical(FLERR, arg[++iarg], false, lmp);
     } else {
-      error->all(FLERR, "Illegal fix electrode/conp command");
+      error->all(FLERR, "Unknown keyword {} for fix {} command", arg[iarg], style);
     }
     iarg++;
   }
@@ -241,9 +241,7 @@ FixElectrodeConp::FixElectrodeConp(LAMMPS *lmp, int narg, char **arg) :
   }
   if (read_inv && read_mat) error->all(FLERR, "Cannot read matrix from two files");
   if (write_mat && read_inv)
-    error->all(FLERR,
-               "Cannot write elastance matrix if reading capacitance matrix "
-               "from file");
+    error->all(FLERR, "Cannot write elastance matrix if reading capacitance matrix from file");
   num_of_groups = static_cast<int>(groups.size());
   size_vector = num_of_groups;
   array_flag = !!(algo == Algo::MATRIX_INV);
@@ -291,7 +289,7 @@ FixElectrodeConp::FixElectrodeConp(LAMMPS *lmp, int narg, char **arg) :
 int FixElectrodeConp::modify_param(int narg, char **arg)
 {
   if (strcmp(arg[0], "tf") == 0) {
-    if (narg < 4) error->all(FLERR, fmt::format("Incorrect number of arguments for fix_modify tf"));
+    if (narg < 4) error->all(FLERR, "Incorrect number of arguments for fix_modify {}", style);
     tfflag = true;
     // read atom type, Thomas-Fermi length, and voronoi volume (reciprocal
     // number density)
@@ -323,13 +321,12 @@ int FixElectrodeConp::modify_param(int narg, char **arg)
     return 4;
 
   } else if (strcmp(arg[0], "timer") == 0) {
-    if (narg < 2)
-      error->all(FLERR, fmt::format("Incorrect number of arguments for fix_modify timer"));
+    if (narg < 2) error->all(FLERR, "Incorrect number of arguments for fix_modify {} timer", style);
     timer_flag = utils::logical(FLERR, arg[1], false, lmp);
     return 2;
 
   } else
-    error->all(FLERR, "Invalid argument for fix_modify electrode");
+    error->all(FLERR, "Unknown argument {} for fix_modify {}", arg[0], style);
   return 0;
 }
 
@@ -351,11 +348,11 @@ int FixElectrodeConp::modify_param(const std::string &param_str)
 int FixElectrodeConp::groupnum_from_name(char *groupname)
 {
   int id = group->find(groupname);
-  if (id < 0) error->all(FLERR, fmt::format("Group {} does not exist", groupname));
+  if (id < 0) error->all(FLERR, "Group {} does not exist", groupname);
   for (int g = 0; g < num_of_groups; g++) {
     if (groups[g] == id) return g;
   }
-  error->all(FLERR, fmt::format("Group {} is not coupled by fix electrode", groupname));
+  error->all(FLERR, "Group {} is not coupled by fix electrode", groupname);
   return -1;    // dummy return value
 }
 
@@ -445,7 +442,7 @@ void FixElectrodeConp::setup_post_neighbor()
     }
     MPI_Allreduce(MPI_IN_PLACE, &unset_tf, 1, MPI_INT, MPI_SUM, world);
     if (unset_tf)
-      error->all(FLERR, fmt::format("Thomas-Fermi parameters not set for all types in electrode"));
+      error->all(FLERR, "Thomas-Fermi parameters not set for all types in fix {}", style);
   }
 
   // get equal-style variable ids:
@@ -454,11 +451,9 @@ void FixElectrodeConp::setup_post_neighbor()
     if (group_psi_var_styles[g] == VarStyle::CONST) continue;
     const char *var_name = group_psi_var_names[g].c_str();
     int var_id = input->variable->find(var_name);
-    if (var_id < 0)
-      error->all(FLERR, fmt::format("Variable '{}' for fix electrode does not exist", var_name));
+    if (var_id < 0) error->all(FLERR, "Variable '{}' for fix {} does not exist", var_name, style);
     if (!input->variable->equalstyle(var_id))
-      error->all(FLERR,
-                 fmt::format("Variable '{}' for fix electrode is not equal-style", var_name));
+      error->all(FLERR, "Variable '{}' for fix {} is not equal-style", var_name, style);
     group_psi_var_ids[g] = var_id;
   }
 
@@ -508,9 +503,8 @@ void FixElectrodeConp::setup_post_neighbor()
     if (comm->me == 0 && write_mat) {
       auto f_mat = fopen(output_file_mat.c_str(), "w");
       if (f_mat == nullptr)
-        error->one(FLERR,
-                   fmt::format("Cannot open elastance matrix file {}: {}", output_file_mat,
-                               utils::getsyserror()));
+        error->one(FLERR, "Cannot open elastance matrix file {}: {}", output_file_mat,
+                   utils::getsyserror());
       write_to_file(f_mat, taglist_bygroup, order_matrix(group_idx, elastance));
       fclose(f_mat);
     }
@@ -534,8 +528,7 @@ void FixElectrodeConp::setup_post_neighbor()
       compute_macro_matrices();
       MPI_Barrier(world);
       if (timer_flag && (comm->me == 0))
-        utils::logmesg(
-            lmp, fmt::format("SD-vector and macro matrices time: {:.4g} s\n", MPI_Wtime() - start));
+        utils::logmesg(lmp, "SD-vector and macro matrices time: {:.4g} s\n", MPI_Wtime() - start);
     }
   }
   // initial charges and b vector
@@ -550,11 +543,9 @@ void FixElectrodeConp::setup_post_neighbor()
     if (comm->me == 0) {
       auto f_vec = fopen(output_file_vec.c_str(), "w");
       if (f_vec == nullptr)
-        error->one(
-            FLERR,
-            fmt::format("Cannot open vector file {}: {}", output_file_vec, utils::getsyserror()));
+        error->one(FLERR, "Cannot open vector file {}: {}", output_file_vec, utils::getsyserror());
       std::vector<std::vector<double>> vec(ngroup, std::vector<double>(1));
-      for (int i = 0; i < ngroup; i++) { vec[group_idx[i]][0] = potential_iele[i]; }
+      for (int i = 0; i < ngroup; i++) vec[group_idx[i]][0] = potential_iele[i];
       write_to_file(f_vec, taglist_bygroup, vec);
       fclose(f_vec);
     }
@@ -564,9 +555,8 @@ void FixElectrodeConp::setup_post_neighbor()
     if (comm->me == 0) {
       auto f_inv = fopen(output_file_inv.c_str(), "w");
       if (f_inv == nullptr)
-        error->one(FLERR,
-                   fmt::format("Cannot open capacitance matrix file {}: {}", output_file_inv,
-                               utils::getsyserror()));
+        error->one(FLERR, "Cannot open capacitance matrix file {}: {}", output_file_inv,
+                   utils::getsyserror());
       write_to_file(f_inv, taglist_bygroup, order_matrix(group_idx, capacitance));
       fclose(f_inv);
     }
@@ -603,7 +593,7 @@ void FixElectrodeConp::invert()
   if (info_rf != 0 || info_ri != 0) error->all(FLERR, "CONP matrix inversion failed!");
   MPI_Barrier(world);
   if (timer_flag && (comm->me == 0))
-    utils::logmesg(lmp, fmt::format("Invert time: {:.4g} s\n", MPI_Wtime() - invert_time));
+    utils::logmesg(lmp, "Invert time: {:.4g} s\n", MPI_Wtime() - invert_time);
 }
 
 /* ---------------------------------------------------------------------- */
@@ -694,9 +684,9 @@ void FixElectrodeConp::setup_pre_exchange()    // create_taglist
   mem_needed /= (1024 * 1024 * 1024);    // convert to GiB
   if (mem_needed > 0.5 && comm->me == 0)
     error->warning(FLERR,
-                   fmt::format("Please ensure there is sufficient memory for fix electrode "
-                               "(anticipated usage is at least {:.1f} GiB per proc)",
-                               mem_needed));
+                   "Please ensure there is sufficient memory for fix electrode "
+                   "(anticipated usage is at least {:.1f} GiB per proc)",
+                   mem_needed);
 }
 
 /* ---------------------------------------------------------------------- */
@@ -867,7 +857,7 @@ void FixElectrodeConp::update_charges()
   update_time += MPI_Wtime() - start;
 }
 
-std::vector<double> FixElectrodeConp::ele_ele_interaction(const std::vector<double>& q_local)
+std::vector<double> FixElectrodeConp::ele_ele_interaction(const std::vector<double> &q_local)
 {
   assert(q_local.size() == nlocalele);
   assert(algo == Algo::CG || algo == Algo::MATRIX_CG);
@@ -1211,13 +1201,11 @@ FixElectrodeConp::~FixElectrodeConp()
   if (comm->me == 0) {
     try {
       if (timer_flag) {
-        utils::logmesg(lmp, fmt::format("Multiplication time: {:.4g} s\n", mult_time));
-        utils::logmesg(lmp, fmt::format("Update time: {:.4g} s\n", update_time));
+        utils::logmesg(lmp, "Multiplication time: {:.4g} s\n", mult_time);
+        utils::logmesg(lmp, "Update time: {:.4g} s\n", update_time);
       }
       if (algo == Algo::CG || algo == Algo::MATRIX_CG)
-        utils::logmesg(
-            lmp,
-            fmt::format("Average conjugate gradient steps: {:.4g}\n", n_cg_step * 1. / n_call));
+        utils::logmesg(lmp, "Average conjugate gradient steps: {:.4g}\n", n_cg_step * 1. / n_call);
     } catch (std::exception &) {
     }
   }
@@ -1304,7 +1292,7 @@ void FixElectrodeConp::read_from_file(const std::string &input_file, double **ar
       }
     }
     if ((bigint) idx.size() != ngroup)
-      error->all(FLERR, fmt::format("Read tags do not match taglist of electrode/conp"));
+      error->all(FLERR, "Read tags do not match taglist of fix {}", style);
     for (bigint i = 0; i < ngroup; i++) {
       bigint const ii = idx[i];
       for (bigint j = 0; j < ngroup; j++) array[i][j] = matrix[ii][idx[j]];