Picasso IllegalArgumentException Target must not be null

make sure you inflating the correct xml That was my problem since I copied an already existing adapter and forgot to change that

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(context)
            .inflate(R.layout.list_item_subcategories, parent, false);

Where the layout I should have put was list_item_categories

image is the target passed to into. It is what's null.

Ensure that your layout IDs are correct for all configurations and specify @+id/details_image.