BERT-CNN: conv2d() received an invalid combination of arguments

I’m trying to fine-tune a BERT model with a CNN layer on top, but get the error:

conv2d() received an invalid combination of arguments - got (Tensor, Parameter, Parameter, tuple, tuple, tuple, int), but expected one of:

  • (Tensor input, Tensor weight, Tensor bias, tuple of ints stride, tuple of ints padding, tuple of ints dilation, int groups) didn’t match because some of the arguments have invalid types: (Tensor, !Parameter!, !Parameter!, !tuple!, !tuple!, !tuple!, int)
from transformers import BertModel, BertTokenizer, AdamW
import torch.nn as nn
import pytorch_lightning as pl

class CommentModule(pl.LightningModule):
  def __init__(self, n_classes=13):
      self.bert = BertModel.from_pretrained('bert-base-uncased')
      self.conv = nn.Conv2d(in_channels=13, out_channels=13, kernel_size=(3, 768), padding=True)
      self.relu = nn.ReLU()
      self.pool = nn.MaxPool2d(kernel_size=3, stride=1)
      self.dropout = nn.Dropout(0.1)
      self.fc = nn.Linear(442, 3)
      self.flat = nn.Flatten()
      self.softmax = nn.LogSoftmax(dim=1)

  def forward(self, input_ids, attention_mask, labels=None):
      # outputs[2]  = [13, 32, 128, 768] 
      outputs = self.bert(input_ids, attention_mask, output_hidden_states=True)

      # x now of shape = [32, 13, 128, 768] 
      # ([13 layers?, 32=batch size, 128=max_seq_length, 729=BERT hidden size)
      x = torch.transpose([t.unsqueeze(0) for t in outputs[2]]), 0), 0, 1)

      x = self.dropout(x)

      ########### ERROR OCCURS AT self.conv(x)
      x = self.conv(x)

      x = self.relu(x)
      x = self.dropout(x)
      x = self.pool(x)
      x = self.fc(self.dropout(self.flat(self.dropout(x))))
      return self.softmax(x)

  def training_step(self, batch, batch_idx):
    input_ids = batch['input_ids']
    attention_mask = batch['attention_mask']
    labels = batch['labels']
    loss, outputs = self.forward(input_ids, attention_mask, labels)
    return {'loss': loss, 'predictions': outputs, 'labels': labels}

Notice that my received arguments are “(Tensor, Parameter, Parameter, tuple, tuple, tuple, int)”, while the expected arguments are “(Tensor input, Tensor weight, Tensor bias, tuple of ints stride, tuple of ints padding, tuple of ints dilation, int groups)”. These almost match?

Conv1d() accepts 3 arguments (Conv2d accepts 4): If I set output_hidden_states=False and pass in the 3 resulting arguments to Conv1d, I get the exact same error. I’m really not sure what the problem is. outputs[0] and outputs[1] are tensors, output[2] is a tuple with shape (32, 13, 128, 768) (batch_size, input_layers, sequence_length, BERT hidden size) if that helps.

I’m admittedly only addressing the error you’re getting. There is no padding=True option in the docs for Conv2d layers. Setting that to padding='same' should eliminate the error.

import torch
import torch.nn as nn

conv = nn.Conv2d(in_channels=13, out_channels=13, kernel_size=(3, 3), padding='same')

dummy_tensor = torch.rand((32,13,128,768))


I’ve reduced the kernel_size in the above example to 3x3 as setting it to 3x768 will make the calculation take a very long time.

Certainly didn’t expect the solution to be changing a false parameter type, but it did solve the error in question. Thank you!

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