diff --git a/docs/source/capi/index.rst b/docs/source/capi/index.rst
index fbc2830b56..85509f6f43 100644
--- a/docs/source/capi/index.rst
+++ b/docs/source/capi/index.rst
@@ -46,10 +46,13 @@ Type Definitions
 Functions
 ---------
 
-.. c:function:: void openmc_calculate_volumes()
+.. c:function:: int openmc_calculate_volumes()
 
    Run a stochastic volume calculation
 
+   :return: Return status (negative if an error occurred)
+   :rtype: int
+
 .. c:function:: int openmc_cell_get_fill(int32_t index, int* type, int32_t** indices, int32_t* n)
 
    Get the fill for a cell
@@ -192,11 +195,14 @@ Functions
    :return: Return status (negative if an error occurred)
    :rtype: int
 
-.. c:function:: void openmc_finalize()
+.. c:function:: int openmc_finalize()
 
    Finalize a simulation
 
-.. c:function:: void openmc_find(double* xyz, int rtype, int32_t* id, int32_t* instance)
+   :return: Return status (negative if an error occurs)
+   :rtype: int
+
+.. c:function:: int openmc_find(double* xyz, int rtype, int32_t* id, int32_t* instance)
 
    Determine the ID of the cell/material containing a given point
 
@@ -207,6 +213,8 @@ Functions
                        occurs, the ID is -1.
    :param int32_t* instance: If a cell is repeated in the geometry, the instance
                              of the cell that was found and zero otherwise.
+   :return: Return status (negative if an error occurs)
+   :rtype: int
 
 .. c:function:: int openmc_get_cell_index(int32_t id, int32_t* index)
 
@@ -266,11 +274,14 @@ Functions
    :return: Return status (negative if an error occurs)
    :rtype: int
 
-.. c:function:: void openmc_hard_reset()
+.. c:function:: int openmc_hard_reset()
 
    Reset tallies, timers, and pseudo-random number generator state
 
-.. c:function:: void openmc_init(int argc, char** argv, const void* intracomm)
+   :return: Return status (negative if an error occurs)
+   :rtype: int
+
+.. c:function:: int openmc_init(int argc, char** argv, const void* intracomm)
 
    Initialize OpenMC
 
@@ -279,6 +290,8 @@ Functions
    :param intracomm: MPI intracommunicator. If MPI is not being used, a null
                      pointer should be passed.
    :type intracomm: const void*
+   :return: Return status (negative if an error occurs)
+   :rtype: int
 
 .. c:function:: int openmc_load_nuclide(char name[])
 
@@ -396,26 +409,41 @@ Functions
    :return: Return status (negative if an error occurs)
    :rtype: int
 
-.. c:function:: void openmc_plot_geometry()
+.. c:function:: int openmc_plot_geometry()
 
    Run plotting mode.
 
-.. c:function:: void openmc_reset()
+   :return: Return status (negative if an error occurs)
+   :rtype: int
+
+.. c:function:: int openmc_reset()
 
    Resets all tally scores
 
-.. c:function:: void openmc_run()
+   :return: Return status (negative if an error occurs)
+   :rtype: int
+
+.. c:function:: int openmc_run()
 
    Run a simulation
 
-.. c:function:: void openmc_simulation_finalize()
+   :return: Return status (negative if an error occurs)
+   :rtype: int
+
+.. c:function:: int openmc_simulation_finalize()
 
    Finalize a simulation.
 
-.. c:function:: void openmc_simulation_init()
+   :return: Return status (negative if an error occurs)
+   :rtype: int
+
+.. c:function:: int openmc_simulation_init()
 
    Initialize a simulation. Must be called after openmc_init().
 
+   :return: Return status (negative if an error occurs)
+   :rtype: int
+
 .. c:function:: int openmc_source_bank(struct Bank** ptr, int64_t* n)
 
    Return a pointer to the source bank array.
@@ -435,13 +463,15 @@ Functions
    :return: Return status (negative if an error occurred)
    :rtype: int
 
-.. c:function:: void openmc_statepoint_write(const char filename[])
+.. c:function:: int openmc_statepoint_write(const char filename[])
 
    Write a statepoint file
 
    :param filename: Name of file to create. If a null pointer is passed, a
                     filename is assigned automatically.
    :type filename: const char[]
+   :return: Return status (negative if an error occurs)
+   :rtype: int
 
 .. c:function:: int openmc_tally_get_id(int32_t index, int32_t* id)
 
diff --git a/include/openmc.h b/include/openmc.h
index 0556187419..38b7f21670 100644
--- a/include/openmc.h
+++ b/include/openmc.h
@@ -4,7 +4,6 @@
 #include <stdint.h>
 #include <stdbool.h>
 
-
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -17,7 +16,7 @@ extern "C" {
     int delayed_group;
   };
 
-  void openmc_calculate_volumes();
+  int openmc_calculate_volumes();
   int openmc_cell_get_fill(int32_t index, int* type, int32_t** indices, int32_t* n);
   int openmc_cell_get_id(int32_t index, int32_t* id);
   int openmc_cell_set_fill(int32_t index, int type, int32_t n, const int32_t* indices);
@@ -35,7 +34,7 @@ extern "C" {
   int openmc_filter_get_type(int32_t index, const char** type);
   int openmc_filter_set_id(int32_t index, int32_t id);
   int openmc_filter_set_type(int32_t index, const char* type);
-  void openmc_finalize();
+  int openmc_finalize();
   int openmc_find(double* xyz, int rtype, int32_t* id, int32_t* instance);
   int openmc_get_cell_index(int32_t id, int32_t* index);
   int openmc_get_filter_index(int32_t id, int32_t* index);
@@ -46,7 +45,7 @@ extern "C" {
   int openmc_get_nuclide_index(const char name[], int* index);
   int64_t openmc_get_seed();
   int openmc_get_tally_index(int32_t id, int32_t* index);
-  void openmc_hard_reset();
+  int openmc_hard_reset();
   int openmc_init(int argc, char* argv[], const void* intracomm);
   int openmc_init_f(const int* intracomm);
   int openmc_legendre_filter_get_order(int32_t index, int* order);
@@ -73,12 +72,12 @@ extern "C" {
   int openmc_next_batch(int* status);
   int openmc_nuclide_name(int index, char** name);
   int openmc_particle_restart();
-  void openmc_plot_geometry();
-  void openmc_reset();
+  int openmc_plot_geometry();
+  int openmc_reset();
   int openmc_run();
   void openmc_set_seed(int64_t new_seed);
-  void openmc_simulation_finalize();
-  void openmc_simulation_init();
+  int openmc_simulation_finalize();
+  int openmc_simulation_init();
   int openmc_source_bank(struct Bank** ptr, int64_t* n);
   int openmc_source_set_strength(int32_t index, double strength);
   int openmc_spatial_legendre_filter_get_order(int32_t index, int* order);
@@ -90,7 +89,7 @@ extern "C" {
   int openmc_sphharm_filter_get_cosine(int32_t index, char cosine[]);
   int openmc_sphharm_filter_set_order(int32_t index, int order);
   int openmc_sphharm_filter_set_cosine(int32_t index, const char cosine[]);
-  void openmc_statepoint_write(const char filename[]);
+  int openmc_statepoint_write(const char filename[]);
   int openmc_tally_get_active(int32_t index, bool* active);
   int openmc_tally_get_id(int32_t index, int32_t* id);
   int openmc_tally_get_filters(int32_t index, int32_t** indices, int* n);
diff --git a/openmc/capi/core.py b/openmc/capi/core.py
index 1c2725382f..273f0c0c7f 100644
--- a/openmc/capi/core.py
+++ b/openmc/capi/core.py
@@ -20,32 +20,41 @@ class _Bank(Structure):
                 ('delayed_group', c_int)]
 
 
-_dll.openmc_calculate_volumes.restype = None
-_dll.openmc_finalize.restype = None
+_dll.openmc_calculate_volumes.restype = c_int
+_dll.openmc_calculate_volumes.errcheck = _error_handler
+_dll.openmc_finalize.restype = c_int
+_dll.openmc_finalize.errcheck = _error_handler
 _dll.openmc_find.argtypes = [POINTER(c_double*3), c_int, POINTER(c_int32),
                              POINTER(c_int32)]
 _dll.openmc_find.restype = c_int
 _dll.openmc_find.errcheck = _error_handler
-_dll.openmc_hard_reset.restype = None
+_dll.openmc_hard_reset.restype = c_int
+_dll.openmc_hard_reset.errcheck = _error_handler
 _dll.openmc_init.argtypes = [c_int, POINTER(c_char_p), c_void_p]
-_dll.openmc_init.restype = None
+_dll.openmc_init.restype = c_int
+_dll.openmc_init.errcheck = _error_handler
 _dll.openmc_get_keff.argtypes = [POINTER(c_double*2)]
 _dll.openmc_get_keff.restype = c_int
 _dll.openmc_get_keff.errcheck = _error_handler
 _dll.openmc_next_batch.argtypes = [POINTER(c_int)]
 _dll.openmc_next_batch.restype = c_int
 _dll.openmc_next_batch.errcheck = _error_handler
-_dll.openmc_plot_geometry.restype = None
+_dll.openmc_plot_geometry.restype = c_int
+_dll.openmc_plot_geometry.restype = _error_handler
 _dll.openmc_run.restype = c_int
 _dll.openmc_run.errcheck = _error_handler
-_dll.openmc_reset.restype = None
+_dll.openmc_reset.restype = c_int
+_dll.openmc_reset.errcheck = _error_handler
 _dll.openmc_source_bank.argtypes = [POINTER(POINTER(_Bank)), POINTER(c_int64)]
 _dll.openmc_source_bank.restype = c_int
 _dll.openmc_source_bank.errcheck = _error_handler
-_dll.openmc_simulation_init.restype = None
-_dll.openmc_simulation_finalize.restype = None
+_dll.openmc_simulation_init.restype = c_int
+_dll.openmc_simulation_init.errcheck = _error_handler
+_dll.openmc_simulation_finalize.restype = c_int
+_dll.openmc_simulation_finalize.errcheck = _error_handler
 _dll.openmc_statepoint_write.argtypes = [POINTER(c_char_p)]
-_dll.openmc_statepoint_write.restype = None
+_dll.openmc_statepoint_write.restype = c_int
+_dll.openmc_statepoint_write.errcheck = _error_handler
 
 
 def calculate_volumes():
diff --git a/src/api.F90 b/src/api.F90
index bf760770b5..49d86edb67 100644
--- a/src/api.F90
+++ b/src/api.F90
@@ -102,14 +102,11 @@ contains
 ! variables
 !===============================================================================
 
-  subroutine openmc_finalize() bind(C)
-
-#ifdef OPENMC_MPI
-    integer :: err
-#endif
+  function openmc_finalize() result(err) bind(C)
+    integer(C_INT) :: err
 
     ! Clear results
-    call openmc_reset()
+    err = openmc_reset()
 
     ! Reset global variables
     assume_separate = .false.
@@ -169,12 +166,13 @@ contains
     ! Deallocate arrays
     call free_memory()
 
+    err = 0
 #ifdef OPENMC_MPI
     ! Free all MPI types
     call MPI_TYPE_FREE(MPI_BANK, err)
 #endif
 
-  end subroutine openmc_finalize
+  end function openmc_finalize
 
 !===============================================================================
 ! OPENMC_FIND determines the ID or a cell or material at a given point in space
@@ -225,9 +223,11 @@ contains
 ! generator state
 !===============================================================================
 
-  subroutine openmc_hard_reset() bind(C)
+  function openmc_hard_reset() result(err) bind(C)
+    integer(C_INT) :: err
+
     ! Reset all tallies and timers
-    call openmc_reset()
+    err = openmc_reset()
 
     ! Reset total generations and keff guess
     keff = ONE
@@ -235,13 +235,15 @@ contains
 
     ! Reset the random number generator state
     call openmc_set_seed(DEFAULT_SEED)
-  end subroutine openmc_hard_reset
+  end function openmc_hard_reset
 
 !===============================================================================
 ! OPENMC_RESET resets tallies and timers
 !===============================================================================
 
-  subroutine openmc_reset() bind(C)
+  function openmc_reset() result(err) bind(C)
+    integer(C_INT) :: err
+
     integer :: i
 
     if (allocated(tallies)) then
@@ -289,7 +291,8 @@ contains
     call time_transport % reset()
     call time_finalize % reset()
 
-  end subroutine openmc_reset
+    err = 0
+  end function openmc_reset
 
 !===============================================================================
 ! FREE_MEMORY deallocates and clears  all global allocatable arrays in the
diff --git a/src/main.cpp b/src/main.cpp
index 5bf305093b..b9e475cd71 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -29,13 +29,13 @@ int main(int argc, char* argv[]) {
     err = openmc_run();
     break;
   case RUN_MODE_PLOTTING:
-    openmc_plot_geometry();
+    err = openmc_plot_geometry();
     break;
   case RUN_MODE_PARTICLE:
     if (openmc_master) err = openmc_particle_restart();
     break;
   case RUN_MODE_VOLUME:
-    openmc_calculate_volumes();
+    err = openmc_calculate_volumes();
     break;
   }
 
diff --git a/src/plot.F90 b/src/plot.F90
index c2ffa2d39c..f17ac33511 100644
--- a/src/plot.F90
+++ b/src/plot.F90
@@ -30,7 +30,8 @@ contains
 ! RUN_PLOT controls the logic for making one or many plots
 !===============================================================================
 
-  subroutine openmc_plot_geometry() bind(C)
+  function openmc_plot_geometry() result(err) bind(C)
+    integer(C_INT) :: err
 
     integer :: i ! loop index for plots
 
@@ -50,7 +51,8 @@ contains
       end associate
     end do
 
-  end subroutine openmc_plot_geometry
+    err = 0
+  end function openmc_plot_geometry
 
 !===============================================================================
 ! POSITION_RGB computes the red/green/blue values for a given plot with the
diff --git a/src/simulation.F90 b/src/simulation.F90
index e9729df038..4f6163429e 100644
--- a/src/simulation.F90
+++ b/src/simulation.F90
@@ -312,6 +312,7 @@ contains
 
   subroutine finalize_batch()
 
+    integer(C_INT) :: err
 #ifdef OPENMC_MPI
     integer :: mpi_err ! MPI error code
 #endif
@@ -347,7 +348,7 @@ contains
 
     ! Write out state point if it's been specified for this batch
     if (statepoint_batch % contains(current_batch)) then
-      call openmc_statepoint_write()
+      err = openmc_statepoint_write()
     end if
 
     ! Write out source point if it's been specified for this batch
@@ -396,9 +397,13 @@ contains
 ! INITIALIZE_SIMULATION
 !===============================================================================
 
-  subroutine openmc_simulation_init() bind(C)
+  function openmc_simulation_init() result(err) bind(C)
+    integer(C_INT) :: err
+
     integer :: i
 
+    err = 0
+
     ! Skip if simulation has already been initialized
     if (simulation_initialized) return
 
@@ -456,14 +461,15 @@ contains
     ! Set flag indicating initialization is done
     simulation_initialized = .true.
 
-  end subroutine openmc_simulation_init
+  end function openmc_simulation_init
 
 !===============================================================================
 ! FINALIZE_SIMULATION calculates tally statistics, writes tallies, and displays
 ! execution time and results
 !===============================================================================
 
-  subroutine openmc_simulation_finalize() bind(C)
+  function openmc_simulation_finalize() result(err) bind(C)
+    integer(C_INT) :: err
 
     integer    :: i       ! loop index
 #ifdef OPENMC_MPI
@@ -479,6 +485,8 @@ contains
 #endif
 #endif
 
+    err = 0
+
     ! Skip if simulation was never run
     if (.not. simulation_initialized) return
 
@@ -553,7 +561,7 @@ contains
     need_depletion_rx = .false.
     simulation_initialized = .false.
 
-  end subroutine openmc_simulation_finalize
+  end function openmc_simulation_finalize
 
 !===============================================================================
 ! CALCULATE_WORK determines how many particles each processor should simulate
diff --git a/src/state_point.F90 b/src/state_point.F90
index 5b1c4d462a..005b549c30 100644
--- a/src/state_point.F90
+++ b/src/state_point.F90
@@ -58,8 +58,9 @@ contains
 ! OPENMC_STATEPOINT_WRITE writes an HDF5 statepoint file to disk
 !===============================================================================
 
-  subroutine openmc_statepoint_write(filename) bind(C)
+  function openmc_statepoint_write(filename) result(err) bind(C)
     type(C_PTR), intent(in), optional :: filename
+    integer(C_INT) :: err
 
     integer :: i, j, k
     integer :: i_xs
@@ -70,12 +71,12 @@ contains
     integer(HID_T) :: cmfd_group, tallies_group, tally_group, meshes_group, &
                       filters_group, filter_group, derivs_group, &
                       deriv_group, runtime_group
-    integer(C_INT) :: err
     real(C_DOUBLE) :: k_combined(2)
     character(MAX_WORD_LEN), allocatable :: str_array(:)
     character(C_CHAR), pointer :: string(:)
     character(len=:, kind=C_CHAR), allocatable :: filename_
 
+    err = 0
     if (present(filename)) then
       call c_f_pointer(filename, string, [MAX_FILE_LEN])
       filename_ = to_f_string(string)
@@ -458,7 +459,7 @@ contains
 
       call file_close(file_id)
     end if
-  end subroutine openmc_statepoint_write
+  end function openmc_statepoint_write
 
 !===============================================================================
 ! WRITE_SOURCE_POINT
diff --git a/src/volume_calc.F90 b/src/volume_calc.F90
index fa770c1f37..8264797a7a 100644
--- a/src/volume_calc.F90
+++ b/src/volume_calc.F90
@@ -36,9 +36,10 @@ contains
 ! the user has specified and writes results to HDF5 files
 !===============================================================================
 
-  subroutine openmc_calculate_volumes() bind(C)
+  function openmc_calculate_volumes() result(err) bind(C)
     integer :: i, j
     integer :: n
+    integer(C_INT) :: err
     real(8), allocatable :: volume(:,:)  ! volume mean/stdev in each domain
     character(10) :: domain_type
     character(MAX_FILE_LEN) :: filename  ! filename for HDF5 file
@@ -99,7 +100,8 @@ contains
       call write_message("Elapsed time: " // trim(to_str(time_volume % &
            get_value())) // " s", 6)
     end if
-  end subroutine openmc_calculate_volumes
+    err = 0
+  end function openmc_calculate_volumes
 
 !===============================================================================
 ! GET_VOLUME stochastically determines the volume of a set of domains along with