ImportError: cannot import name 'MultiScaleDeformableAttention' from 'mmcv.cnn.bricks.transformer'

Thanks for reporting the unexpected results and we appreciate it a lot.

Checklist

1. I have searched related issues but cannot get the expected help.
2. I have read the FAQ documentation but cannot get the expected help.
3. The unexpected results still exist in the latest version.

Describe the Issue

/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmcv/cnn/bricks/transformer.py:28: UserWarning: Fail to import ``MultiScaleDeformableAttention`` from ``mmcv.ops.multi_scale_deform_attn``, You should install ``mmcv-full`` if you need this module. 
  warnings.warn('Fail to import ``MultiScaleDeformableAttention`` from '
/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmdet/models/utils/transformer.py:26: UserWarning: `MultiScaleDeformableAttention` in MMCV has been moved to `mmcv.ops.multi_scale_deform_attn`, please update your MMCV
  warnings.warn(
Traceback (most recent call last):
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmdet/models/utils/transformer.py", line 23, in <module>
    from mmcv.ops.multi_scale_deform_attn import MultiScaleDeformableAttention
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmcv/ops/__init__.py", line 2, in <module>
    from .ball_query import ball_query
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmcv/ops/ball_query.py", line 7, in <module>
    ext_module = ext_loader.load_ext('_ext', ['ball_query_forward'])
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmcv/utils/ext_loader.py", line 13, in load_ext
    ext = importlib.import_module('mmcv.' + name)
  File "/home/zuppif/miniconda3/lib/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
ImportError: /home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmcv/_ext.cpython-39-x86_64-linux-gnu.so: undefined symbol: _ZNK2at6Tensor6deviceEv

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/zuppif/integration-object-detection-icevision/notebook.py", line 7, in <module>
    from icevision import ObjectDetectionRecord, Parser, ClassMap, BBox, ImgSize
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/icevision/__init__.py", line 7, in <module>
    from icevision import models
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/icevision/models/__init__.py", line 15, in <module>
    from icevision.models import mmdet
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/icevision/models/mmdet/__init__.py", line 1, in <module>
    from icevision.models.mmdet import common
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/icevision/models/mmdet/common/__init__.py", line 3, in <module>
    from icevision.models.mmdet.common import bbox
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/icevision/models/mmdet/common/bbox/__init__.py", line 1, in <module>
    from icevision.models.mmdet.common.bbox.dataloaders import *
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/icevision/models/mmdet/common/bbox/dataloaders.py", line 10, in <module>
    from icevision.models.mmdet.common.utils import convert_background_from_zero_to_last
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/icevision/models/mmdet/common/utils.py", line 11, in <module>
    from mmdet.models import build_detector
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmdet/models/__init__.py", line 2, in <module>
    from .backbones import *  # noqa: F401,F403
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmdet/models/backbones/__init__.py", line 2, in <module>
    from .csp_darknet import CSPDarknet
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmdet/models/backbones/csp_darknet.py", line 11, in <module>
    from ..utils import CSPLayer
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmdet/models/utils/__init__.py", line 16, in <module>
    from .transformer import (DetrTransformerDecoder, DetrTransformerDecoderLayer,
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmdet/models/utils/transformer.py", line 29, in <module>
    from mmcv.cnn.bricks.transformer import MultiScaleDeformableAttention
ImportError: cannot import name 'MultiScaleDeformableAttention' from 'mmcv.cnn.bricks.transformer' (/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmcv/cnn/bricks/transformer.py)

Reproduction

Install mmcv-full using mim or

pip install mmcv-full -f https://download.openmmlab.com/mmcv/dist/cu102/torch1.9.1/index.html

then try to use vfnet

Environment

1. Please run python -c "from mmcv.utils import collect_env; print(collect_env())" to collect necessary environment information
   It results in an error

 python -c "from mmcv.utils import collect_env; print(collect_env())"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmcv/utils/env.py", line 87, in collect_env
    from mmcv.ops import get_compiler_version, get_compiling_cuda_version
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmcv/ops/__init__.py", line 2, in <module>
    from .ball_query import ball_query
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmcv/ops/ball_query.py", line 7, in <module>
    ext_module = ext_loader.load_ext('_ext', ['ball_query_forward'])
  File "/home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmcv/utils/ext_loader.py", line 13, in load_ext
    ext = importlib.import_module('mmcv.' + name)
  File "/home/zuppif/miniconda3/lib/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
ImportError: /home/zuppif/integration-object-detection-icevision/.venv/lib/python3.9/site-packages/mmcv/_ext.cpython-39-x86_64-linux-gnu.so: undefined symbol: _ZNK2at6Tensor6deviceEv

[Matesanz]

The problem is that ImportError in this line in is silently catching another exception rather than the “install mmcv-full” one.

if you try the line that is raising the Error:

from mmcv.ops.multi_scale_deform_attn import MultiScaleDeformableAttention
>>> ImportError: .../lib/python3.9/site-packages/mmcv/_ext.cpython-39-x86_64-linux-gnu.so: undefined symbol: _ZNK2at6Tensor4add_ERKS0_RKN3c106ScalarE

Solution

For me was install mmcv CPU version:

pip install mmcv-full -f https://download.openmmlab.com/mmcv/dist/cpu/torch1.11.0/index.html

[howardchina]

same question, why always the same question?

terminal: python3 -m pip list | grep mmcv-full mmcv-full 1.7.0

error: “/home/data/programs/miniconda3/envs/openmmlab/lib/python3.8/site-packages/mmcv/c nn/bricks/transformer.py:33: UserWarning: Fail to import MultiScaleDeformableA ttention from mmcv.ops.multi_scale_deform_attn, You should install mmcv- full if you need this module.”