The error is raised, if you pass an input with the wrong number of channels to a batchnorm layer as shown here:
bn = nn.BatchNorm2d(144)
x = torch.randn(2, 48, 24, 24)
out = bn(x)
> RuntimeError: running_mean should contain 48 elements not 144

Make sure that the incoming activations has the expected number of channels as specified in the batchnorm layer initialization.