RuntimeError: one of the variables needed for gradient computation has been modified by an inplace operation

LightningModule
1

My first forward pass went on smoothly but then i encounter this runtime error

Variable._execution_engine.run_backward( # Calls into the C++ engine to run the backward pass
RuntimeError: one of the variables needed for gradient computation has been modified by an inplace operation: [torch.cuda.LongTensor [590]] is at version 2; expected version 0 instead. Hint: enable anomaly detection to find the operation that failed to compute its gradient, with torch.autograd.set_detect_anomaly(True).

my training_step is as follows:

def training_step(self, batch, batch_idx=None):
y = batch.y
if y.shape[-1] == 1:
y = y.view(-1)

        seq_len = None

    raw_attn_weight = []
    adj_mat_learned = []
    features = []
    reg_loss = None
        logits, reg_loss_dict = self.model(
            batch,
            return_attention=False, 
            lengths=seq_len, 
            epoch=self.current_epoch, 
            epoch_total=self.args.num_epochs,
        )

if self.args.task == “classification”:
# classification task
if self.args.output_dim == 1:
cls_loss = F.binary_cross_entropy_with_logits(
logits.view(-1),
y,
pos_weight=torch.FloatTensor(self.args.pos_weight).to(
self.device
) if (self.args.pos_weight is not None) else None,
)
else:
cls_loss = F.cross_entropy(logits, y.long())
else:
raise NotImplementedError

    return (
        logits,
        y,
        cls_loss,
        # reg_loss,
        batch.writeout_fn,
        raw_attn_weight,
        adj_mat_learned,
        features,
    )

I can’t figure out why am i getting this error. Can someone help me resolve this.