diff --git a/common/python/nomadcore/md_data_access/MDDataAccess.py b/common/python/nomadcore/md_data_access/MDDataAccess.py
index 36c76b87e16f666f22c24bff094d277768283960..905aab1ece8aa4fe2d3d25971d49e001ed9ce132 100644
--- a/common/python/nomadcore/md_data_access/MDDataAccess.py
+++ b/common/python/nomadcore/md_data_access/MDDataAccess.py
@@ -1206,6 +1206,7 @@ class MDDataAccess(object):
             file_format = self.trajformat
 
         usedefault=True
+        molfile_traj=None
         # Use the given order to check topology
         if self.interfaceorder:
             for interface in self.interfaceorder:
@@ -1220,8 +1221,9 @@ class MDDataAccess(object):
                         elif self.natoms is not None:
                             if self.natoms > 0:
                                 molfile_traj = pym.OpenMolfile(self.trajfile, file_format=filetrajformat, natoms=self.natoms, silent=False)
-                        if molfile_traj.trajectory is not None:
-                            trajhandler_check = molfile_traj
+                        if molfile_traj is not None:
+                            if molfile_traj.trajectory is not None:
+                                trajhandler_check = molfile_traj
                         if trajhandler_check:
                             trajhandler = None
                             trajhandler = self.pymolfile_iread(trajhandler_check)
@@ -1420,8 +1422,9 @@ class MDDataAccess(object):
                     elif self.natoms is not None:
                         if self.natoms > 0:
                             molfile_traj = pym.OpenMolfile(self.trajfile, file_format=filetrajformat, natoms=self.natoms, silent=False)
-                    if molfile_traj.trajectory is not None:
-                        trajhandler_check = molfile_traj
+                    if molfile_traj is not None:
+                        if molfile_traj.trajectory is not None:
+                            trajhandler_check = molfile_traj
                     if trajhandler_check:
                         trajhandler = None
                         trajhandler = self.pymolfile_iread(trajhandler_check)
@@ -1441,8 +1444,9 @@ class MDDataAccess(object):
                     if self.natoms is not None:
                         if self.natoms > 0:
                             molfile_traj = pym.OpenMolfile(self.trajfile, file_format=filetrajformat, natoms=self.natoms, silent=False)
-                    if molfile_traj.trajectory is not None:
-                        trajhandler_check = molfile_traj
+                    if molfile_traj is not None:
+                        if molfile_traj.trajectory is not None:
+                            trajhandler_check = molfile_traj
                     if trajhandler_check:
                         trajhandler = None
                         trajhandler = self.pymolfile_iread(trajhandler_check)