diff --git a/addons/stock/models/stock_picking.py b/addons/stock/models/stock_picking.py
index 60d8c36cbd9..f646b0abf1f 100644
--- a/addons/stock/models/stock_picking.py
+++ b/addons/stock/models/stock_picking.py
@@ -6,7 +6,7 @@ import time
 from ast import literal_eval
 from datetime import date, timedelta
 from itertools import groupby
-from operator import itemgetter
+from operator import attrgetter, itemgetter
 
 from odoo import SUPERUSER_ID, _, api, fields, models
 from odoo.addons.stock.models.stock_move import PROCUREMENT_PRIORITIES
@@ -804,14 +804,15 @@ class Picking(models.Model):
         all_in = True
         pack_move_lines = self.move_line_ids.filtered(lambda ml: ml.package_id == package)
         keys = ['product_id', 'lot_id']
+        keys_ids = ["{}.id".format(fname) for fname in keys]
         precision_digits = self.env['decimal.precision'].precision_get('Product Unit of Measure')
 
         grouped_quants = {}
-        for k, g in groupby(sorted(package.quant_ids, key=itemgetter(*keys)), key=itemgetter(*keys)):
+        for k, g in groupby(sorted(package.quant_ids, key=attrgetter(*keys_ids)), key=itemgetter(*keys)):
             grouped_quants[k] = sum(self.env['stock.quant'].concat(*list(g)).mapped('quantity'))
 
         grouped_ops = {}
-        for k, g in groupby(sorted(pack_move_lines, key=itemgetter(*keys)), key=itemgetter(*keys)):
+        for k, g in groupby(sorted(pack_move_lines, key=attrgetter(*keys_ids)), key=itemgetter(*keys)):
             grouped_ops[k] = sum(self.env['stock.move.line'].concat(*list(g)).mapped('product_qty'))
         if any(not float_is_zero(grouped_quants.get(key, 0) - grouped_ops.get(key, 0), precision_digits=precision_digits) for key in grouped_quants) \
                 or any(not float_is_zero(grouped_ops.get(key, 0) - grouped_quants.get(key, 0), precision_digits=precision_digits) for key in grouped_ops):