Index: fenics-dolfinx/cpp/demo/interpolation-io/main.cpp
===================================================================
--- fenics-dolfinx.orig/cpp/demo/interpolation-io/main.cpp	2025-11-12 15:27:14.779518727 +0100
+++ fenics-dolfinx/cpp/demo/interpolation-io/main.cpp	2025-11-12 15:28:34.478884959 +0100
@@ -7,6 +7,7 @@
 // # Interpolation and IO
 
 #include <basix/finite-element.h>
+#include <bit>
 #include <cmath>
 #include <concepts>
 #include <dolfinx/common/log.h>
@@ -64,12 +65,16 @@
       });
 
 #ifdef HAS_ADIOS2
+  // Adios2 is not well tested on big-endian systems, so skip them
+  if constexpr (std::endian::native != std::endian::big)
+  {
   // Write the function to a VTX file for visualisation, e.g. using
   // ParaView
   io::VTXWriter<U> outfile(mesh->comm(), filename.replace_extension("bp"), {u},
                            "BP4");
   outfile.write(0);
   outfile.close();
+  }
 #endif
 }
 
@@ -183,10 +188,14 @@
 // (jump in the normal component between cells) and the x1 component
 // will appear continuous (continuous tangent component between cells).
 #ifdef HAS_ADIOS2
+  // Adios2 is not well tested on big-endian systems, so skip them
+  if constexpr (std::endian::native != std::endian::big)
+  {
   io::VTXWriter<U> outfile(mesh->comm(), filename.replace_extension("bp"),
                            {u_l}, "BP4");
   outfile.write(0);
   outfile.close();
+  }
 #endif
 }
 
Index: fenics-dolfinx/cpp/demo/interpolation_different_meshes/main.cpp
===================================================================
--- fenics-dolfinx.orig/cpp/demo/interpolation_different_meshes/main.cpp	2025-11-12 15:27:14.779518727 +0100
+++ fenics-dolfinx/cpp/demo/interpolation_different_meshes/main.cpp	2025-11-12 15:29:11.432256585 +0100
@@ -10,6 +10,7 @@
 #include <dolfinx/fem/dolfinx_fem.h>
 #include <dolfinx/io/ADIOS2Writers.h>
 #include <dolfinx/mesh/generation.h>
+#include <bit>
 #include <memory>
 
 using namespace dolfinx;
@@ -83,10 +84,14 @@
     u_hex->interpolate(*u_tet, cells, interpolation_data);
 
 #ifdef HAS_ADIOS2
+    // Adios2 is not well tested on big-endian systems, so skip them
+    if constexpr (std::endian::native != std::endian::big)
+    {
     io::VTXWriter<double> write_tet(mesh_tet->comm(), "u_tet.bp", {u_tet});
     write_tet.write(0);
     io::VTXWriter<double> write_hex(mesh_hex->comm(), "u_hex.bp", {u_hex});
     write_hex.write(0);
+    }
 #endif
   }
   MPI_Finalize();
Index: fenics-dolfinx/cpp/demo/poisson/main.cpp
===================================================================
--- fenics-dolfinx.orig/cpp/demo/poisson/main.cpp	2025-11-12 15:27:14.779518727 +0100
+++ fenics-dolfinx/cpp/demo/poisson/main.cpp	2025-11-12 15:27:14.774116253 +0100
@@ -81,6 +81,7 @@
 
 #include "poisson.h"
 #include <basix/finite-element.h>
+#include <bit>
 #include <cmath>
 #include <dolfinx.h>
 #include <dolfinx/fem/Constant.h>
@@ -251,9 +252,13 @@
     file.write<T>({*u}, 0);
 
 #ifdef HAS_ADIOS2
-    // Save solution in VTX format
-    io::VTXWriter<U> vtx(MPI_COMM_WORLD, "u.bp", {u}, "bp4");
-    vtx.write(0);
+    // Adios2 is not well tested on big-endian systems, so skip them
+    if constexpr (std::endian::native != std::endian::big)
+    {
+      // Save solution in VTX format
+      io::VTXWriter<U> vtx(MPI_COMM_WORLD, "u.bp", {u}, "bp4");
+      vtx.write(0);
+    }
 #endif
   }
 
Index: fenics-dolfinx/python/demo/demo_interpolation-io.py
===================================================================
--- fenics-dolfinx.orig/python/demo/demo_interpolation-io.py	2025-11-12 15:27:14.779518727 +0100
+++ fenics-dolfinx/python/demo/demo_interpolation-io.py	2025-11-12 15:27:14.774808321 +0100
@@ -34,6 +34,7 @@
 from mpi4py import MPI
 
 import numpy as np
+from sys import byteorder
 
 from dolfinx import default_scalar_type, has_adios2, plot
 from dolfinx.fem import Function, functionspace