I don’t know, why the change in backbone would cause this issue, but based on your last post:



 YeongHwa_Jin:

I checked the outputs of layers, but I didn’t find any invalid values. Instead, I found loss is very large value on first epoch, first batch:


it seems that the output activations of the backbone look alright, while the loss is really high (or were the output activations already high?).
In the latter case, I would guess that your current hyperparameters are not suitable for the new backbone and let the model diverge.