i am trying to run modelv1.
now at following stage new error is occurring:
model = tf.train.latest_checkpoint(model_dir)
saver.restore(sess, model)
error:
INFO:tensorflow:Restoring parameters from None

TypeError Traceback (most recent call last)
TypeError: expected bytes, NoneType found

The above exception was the direct cause of the following exception:

SystemError Traceback (most recent call last)
in ()
1 model = tf.train.latest_checkpoint(model_dir)
----> 2 saver.restore(sess, model)

/home/snd/anaconda3/lib/python3.6/site-packages/tensorflow/python/training/saver.py in restore(self, sess, save_path)
1546 logging.info("Restoring parameters from %s", save_path)
1547 sess.run(self.saver_def.restore_op_name,
-> 1548 {self.saver_def.filename_tensor_name: save_path})
1549
1550 @staticmethod

/home/snd/anaconda3/lib/python3.6/site-packages/tensorflow/python/client/session.py in run(self, fetches, feed_dict, options, run_metadata)
787 try:
788 result = self._run(None, fetches, feed_dict, options_ptr,
--> 789 run_metadata_ptr)
790 if run_metadata:
791 proto_data = tf_session.TF_GetBuffer(run_metadata_ptr)

/home/snd/anaconda3/lib/python3.6/site-packages/tensorflow/python/client/session.py in _run(self, handle, fetches, feed_dict, options, run_metadata)
995 if final_fetches or final_targets:
996 results = self._do_run(handle, final_targets, final_fetches,
--> 997 feed_dict_string, options, run_metadata)
998 else:
999 results = []

/home/snd/anaconda3/lib/python3.6/site-packages/tensorflow/python/client/session.py in _do_run(self, handle, target_list, fetch_list, feed_dict, options, run_metadata)
1130 if handle is None:
1131 return self._do_call(_run_fn, self._session, feed_dict, fetch_list,
-> 1132 target_list, options, run_metadata)
1133 else:
1134 return self._do_call(_prun_fn, self._session, handle, feed_dict,

/home/snd/anaconda3/lib/python3.6/site-packages/tensorflow/python/client/session.py in _do_call(self, fn, *args)
1137 def _do_call(self, fn, *args):
1138 try:
-> 1139 return fn(*args)
1140 except errors.OpError as e:
1141 message = compat.as_text(e.message)

/home/snd/anaconda3/lib/python3.6/site-packages/tensorflow/python/client/session.py in _run_fn(session, feed_dict, fetch_list, target_list, options, run_metadata)
1119 return tf_session.TF_Run(session, options,
1120 feed_dict, fetch_list, target_list,
-> 1121 status, run_metadata)
1122
1123 def _prun_fn(session, handle, feed_dict, fetch_list):

SystemError: returned a result with an error set

i would like to know why it is occurring is there any sequence to run different models?