I got the same error following the tutorial exactly, but the FasterRCNN documentation:
https://github.com/pytorch/vision/blob/master/torchvision/models/detection/faster_rcnn.py
suggests that the featmap_names in the MultiScaleROIAlign should be a character, ‘0’, not an integer. I replaced
roi_pooler = torchvision.ops.MultiScaleRoIAlign(featmap_names=[0],
output_size=7,
sampling_ratio=2)
with
roi_pooler = torchvision.ops.MultiScaleRoIAlign(featmap_names=['0'],
output_size=7,
sampling_ratio=2)
and the error on foward pass went away. I haven’t verified that the model finetunes appropriately though.
Hope this helps.