RuntimeError: apex.optimizers.FusedAdam requires cuda extensions

My environment is configured as Windows server2016, torch 1.8.1, torchvision 0.9.1, cuda10.2, apex is successfully installed, but when running the project code (NVlabs/imagenaire), an error is reported:

Initialize net_G and net_D weights using type: orthogonal gain: 1
net_G parameter count: 30,258,966
net_D parameter count: 32,322,498
Traceback (most recent call last):
File "H:\19xyy\project\imaginaire-master\train.py", line 100, in
main()
File "H:\19xyy\project\imaginaire-master\train.py", line 60, in main
get_model_optimizer_and_scheduler(cfg, seed=args.seed)
File "H:\19xyy\project\imaginaire-master\imaginaire\utils\trainer.py", line 115, in get_model_optimizer_and_scheduler
opt_G = get_optimizer(cfg.gen_opt, net_G)
File "H:\19xyy\project\imaginaire-master\imaginaire\utils\trainer.py", line 257, in get_optimizer
return get_optimizer_for_params(cfg_opt, params)
File "H:\19xyy\project\imaginaire-master\imaginaire\utils\trainer.py", line 274, in get_optimizer_for_params
opt = FusedAdam(params,
File "G:\Anaconda3\envs\xyy_imagenaire\lib\site-packages\apex\optimizers\fused_adam.py", line 80, in init
raise RuntimeError('apex.optimizers.FusedAdam requires cuda extensions')
RuntimeError: apex.optimizers.FusedAdam requires cuda extensions

The versions of nvcc -V and print(torch.version.cuda) are the same. I don’t know why this error is reported. Are there any good suggestions to make the code run correctly? Looking forward to your reply, thank you very much！

Start with imaginaire/utils/trainer.py, especially get_optimizer_for_params, and compare its FusedAdam call with apex/optimizers/fused_adam.py where the reported exception is raised. Check how the CUDA extensions were installed for the stated Windows, PyTorch, and CUDA versions, then run train.py to confirm the error no longer occurs.