from torch import nn
from torch.optim import Adam
from torch.optim.lr_scheduler import MultiStepLR

import torch

net = nn.LSTM(10, 10)
optimizer = Adam(params=filter(lambda p: p.requires_grad, net.parameters()))
scheduler = MultiStepLR(optimizer, milestones=[30, 80], gamma=0.1)

scheduler.step()  # This is Fine

# Check save and load into the directory work
torch.save(scheduler, 'scheduler.pt')
scheduler = torch.load('scheduler.pt')

scheduler.step()  # AttributeError: 'MultiStepLR' object has no attribute 'optimizer'

Traceback (most recent call last):
  File "play.py", line 17, in <module>
    scheduler.step()  # AttributeError: 'MultiStepLR' object has no attribute 'optimizer'
  File "/usr/local/lib/python3.6/dist-packages/torch/optim/lr_scheduler.py", line 55, in step
    for param_group, lr in zip(self.optimizer.param_groups, self.get_lr()):
AttributeError: 'MultiStepLR' object has no attribute 'optimizer'