Import_meta_graph failed

I am using tensorflow 1.15. Export the quantizationSimModel and try to freeze the tensorflow model. But the first line of code failed. Anyone can help ?

saver = tf.train.import_meta_graph('./final.meta', clear_devices=False)

File “/home/cvip/tf1.15/lib/python3.6/site-packages/tensorflow_core/python/training/saver.py”, line 1453, in import_meta_graph
**kwargs)[0]
File “/home/cvip/tf1.15/lib/python3.6/site-packages/tensorflow_core/python/training/saver.py”, line 1477, in _import_meta_graph_with_return_elements
**kwargs))
File “/home/cvip/tf1.15/lib/python3.6/site-packages/tensorflow_core/python/framework/meta_graph.py”, line 809, in import_scoped_meta_graph_with_return_elements
return_elements=return_elements)
File “/home/cvip/tf1.15/lib/python3.6/site-packages/tensorflow_core/python/util/deprecation.py”, line 507, in new_func
return func(*args, **kwargs)
File “/home/cvip/tf1.15/lib/python3.6/site-packages/tensorflow_core/python/framework/importer.py”, line 405, in import_graph_def
producer_op_list=producer_op_list)
File “/home/cvip/tf1.15/lib/python3.6/site-packages/tensorflow_core/python/framework/importer.py”, line 517, in _import_graph_def_internal
_ProcessNewOps(graph)
File “/home/cvip/tf1.15/lib/python3.6/site-packages/tensorflow_core/python/framework/importer.py”, line 243, in _ProcessNewOps
for new_op in graph._add_new_tf_operations(compute_devices=False): # pylint: disable=protected-access
File “/home/cvip/tf1.15/lib/python3.6/site-packages/tensorflow_core/python/framework/ops.py”, line 3561, in _add_new_tf_operations
for c_op in c_api_util.new_tf_operations(self)
File “/home/cvip/tf1.15/lib/python3.6/site-packages/tensorflow_core/python/framework/ops.py”, line 3561, in
for c_op in c_api_util.new_tf_operations(self)
File “/home/cvip/tf1.15/lib/python3.6/site-packages/tensorflow_core/python/framework/ops.py”, line 3451, in _create_op_from_tf_operation
ret = Operation(c_op, self)
File “/home/cvip/tf1.15/lib/python3.6/site-packages/tensorflow_core/python/framework/ops.py”, line 1748, in init
self._traceback = tf_stack.extract_stack()