Traceback (most recent call last):


 "<stdin>", line 1, in <module>
ImportError: cannot import name Catalogs

Traceback (most recent call last):


 "./tools/train_net.py", line 18, in <module>

from maskrcnn_benchmark.engine.inference import inference


 "/home/lz/Workspace/maskrcnn-benchmark/maskrcnn_benchmark/engine/inference.py", line 20, in <module>

from maskrcnn_benchmark.structures.boxlist_ops import boxlist_iou


 "/home/lz/Workspace/maskrcnn-benchmark/maskrcnn_benchmark/structures/boxlist_ops.py", line 6, in <module>

from maskrcnn_benchmark.layers import nms as _box_nms


 "/home/lz/Workspace/maskrcnn-benchmark/maskrcnn_benchmark/layers/__init__.py", line 8, in <module>

from .nms import nms


 "/home/lz/Workspace/maskrcnn-benchmark/maskrcnn_benchmark/layers/nms.py", line 3, in <module>

from maskrcnn_benchmark import _C
ImportError: /home/lz/Workspace/maskrcnn-benchmark/maskrcnn_benchmark/_C.cpython-37m-x86_64-linux-gnu.so: undefined symbol: _ZN2at4cuda20getCurrentCUDAStreamEl