diff --git a/addons/stock/models/stock_move_line.py b/addons/stock/models/stock_move_line.py
index dd0635a11f8..2f692feaec3 100644
--- a/addons/stock/models/stock_move_line.py
+++ b/addons/stock/models/stock_move_line.py
@@ -369,14 +369,7 @@ class StockMoveLine(models.Model):
 
                 # Unreserve the old charateristics of the move line.
                 if not ml.move_id._should_bypass_reservation(ml.location_id):
-                    try:
-                        Quant._update_reserved_quantity(ml.product_id, ml.location_id, -ml.reserved_qty, lot_id=ml.lot_id, package_id=ml.package_id, owner_id=ml.owner_id, strict=True)
-                    except UserError:
-                        # If we were not able to unreserve on tracked quants, we can use untracked ones.
-                        if ml.lot_id:
-                            Quant._update_reserved_quantity(ml.product_id, ml.location_id, -ml.reserved_qty, lot_id=False, package_id=ml.package_id, owner_id=ml.owner_id, strict=True)
-                        else:
-                            raise
+                    Quant._update_reserved_quantity(ml.product_id, ml.location_id, -ml.reserved_qty, lot_id=ml.lot_id, package_id=ml.package_id, owner_id=ml.owner_id, strict=True)
 
                 # Reserve the maximum available of the new charateristics of the move line.
                 if not ml.move_id._should_bypass_reservation(updates.get('location_id', ml.location_id)):
@@ -386,14 +379,7 @@ class StockMoveLine(models.Model):
                                                              package_id=updates.get('package_id', ml.package_id), owner_id=updates.get('owner_id', ml.owner_id), strict=True)
                         reserved_qty = sum([x[1] for x in q])
                     except UserError:
-                        if updates.get('lot_id'):
-                            # If we were not able to reserve on tracked quants, we can use untracked ones.
-                            try:
-                                q = Quant._update_reserved_quantity(ml.product_id, updates.get('location_id', ml.location_id), new_reserved_uom_qty, lot_id=False,
-                                                                     package_id=updates.get('package_id', ml.package_id), owner_id=updates.get('owner_id', ml.owner_id), strict=True)
-                                reserved_qty = sum([x[1] for x in q])
-                            except UserError:
-                                pass
+                        pass
                     if reserved_qty != new_reserved_uom_qty:
                         new_reserved_uom_qty = ml.product_id.uom_id._compute_quantity(reserved_qty, ml.product_uom_id, rounding_method='HALF-UP')
                         moves_to_recompute_state |= ml.move_id
@@ -481,13 +467,7 @@ class StockMoveLine(models.Model):
         for ml in self:
             # Unlinking a move line should unreserve.
             if not float_is_zero(ml.reserved_qty, precision_digits=precision) and not ml.move_id._should_bypass_reservation(ml.location_id):
-                try:
-                    self.env['stock.quant']._update_reserved_quantity(ml.product_id, ml.location_id, -ml.reserved_qty, lot_id=ml.lot_id, package_id=ml.package_id, owner_id=ml.owner_id, strict=True)
-                except UserError:
-                    if ml.lot_id:
-                        self.env['stock.quant']._update_reserved_quantity(ml.product_id, ml.location_id, -ml.reserved_qty, lot_id=False, package_id=ml.package_id, owner_id=ml.owner_id, strict=True)
-                    elif not self.env.context.get(MODULE_UNINSTALL_FLAG, False):
-                        raise   # pylint: disable=raise-unlink-override
+                self.env['stock.quant']._update_reserved_quantity(ml.product_id, ml.location_id, -ml.reserved_qty, lot_id=ml.lot_id, package_id=ml.package_id, owner_id=ml.owner_id, strict=True)
         moves = self.mapped('move_id')
         res = super(StockMoveLine, self).unlink()
         if moves:
@@ -588,10 +568,7 @@ class StockMoveLine(models.Model):
                     ml._free_reservation(ml.product_id, ml.location_id, extra_qty, lot_id=ml.lot_id, package_id=ml.package_id, owner_id=ml.owner_id, ml_ids_to_ignore=ml_ids_to_ignore)
                 # unreserve what's been reserved
                 if not ml.move_id._should_bypass_reservation(ml.location_id) and ml.product_id.type == 'product' and ml.reserved_qty:
-                    try:
-                        Quant._update_reserved_quantity(ml.product_id, ml.location_id, -ml.reserved_qty, lot_id=ml.lot_id, package_id=ml.package_id, owner_id=ml.owner_id, strict=True)
-                    except UserError:
-                        Quant._update_reserved_quantity(ml.product_id, ml.location_id, -ml.reserved_qty, lot_id=False, package_id=ml.package_id, owner_id=ml.owner_id, strict=True)
+                    Quant._update_reserved_quantity(ml.product_id, ml.location_id, -ml.reserved_qty, lot_id=ml.lot_id, package_id=ml.package_id, owner_id=ml.owner_id, strict=True)
 
                 # move what's been actually done
                 quantity = ml.product_uom_id._compute_quantity(ml.qty_done, ml.move_id.product_id.uom_id, rounding_method='HALF-UP')
diff --git a/addons/stock/models/stock_quant.py b/addons/stock/models/stock_quant.py
index 2a62632b91e..995867c5787 100644
--- a/addons/stock/models/stock_quant.py
+++ b/addons/stock/models/stock_quant.py
@@ -256,6 +256,8 @@ class StockQuant(models.Model):
                 package_id = self.env['stock.quant.package'].browse(vals.get('package_id'))
                 owner_id = self.env['res.partner'].browse(vals.get('owner_id'))
                 quant = self._gather(product, location, lot_id=lot_id, package_id=package_id, owner_id=owner_id, strict=True)
+                if lot_id:
+                    quant = quant.filtered(lambda q: q.lot_id)
 
                 if quant:
                     quant = quant[0].sudo()
@@ -536,19 +538,19 @@ class StockQuant(models.Model):
         domain = [('product_id', '=', product_id.id)]
         if not strict:
             if lot_id:
-                domain = expression.AND([[('lot_id', '=', lot_id.id)], domain])
+                domain = expression.AND([['|', ('lot_id', '=', lot_id.id), ('lot_id', '=', False)], domain])
             if package_id:
                 domain = expression.AND([[('package_id', '=', package_id.id)], domain])
             if owner_id:
                 domain = expression.AND([[('owner_id', '=', owner_id.id)], domain])
             domain = expression.AND([[('location_id', 'child_of', location_id.id)], domain])
         else:
-            domain = expression.AND([[('lot_id', '=', lot_id and lot_id.id or False)], domain])
+            domain = expression.AND([['|', ('lot_id', '=', lot_id.id), ('lot_id', '=', False)] if lot_id else [('lot_id', '=', False)], domain])
             domain = expression.AND([[('package_id', '=', package_id and package_id.id or False)], domain])
             domain = expression.AND([[('owner_id', '=', owner_id and owner_id.id or False)], domain])
             domain = expression.AND([[('location_id', '=', location_id.id)], domain])
 
-        return self.search(domain, order=removal_strategy_order)
+        return self.search(domain, order=removal_strategy_order).sorted(lambda q: not q.lot_id)
 
     @api.model
     def _get_available_quantity(self, product_id, location_id, lot_id=None, package_id=None, owner_id=None, strict=False, allow_negative=False):
@@ -696,6 +698,8 @@ class StockQuant(models.Model):
         """
         self = self.sudo()
         quants = self._gather(product_id, location_id, lot_id=lot_id, package_id=package_id, owner_id=owner_id, strict=True)
+        if lot_id and quantity > 0:
+            quants = quants.filtered(lambda q: q.lot_id)
 
         if location_id.should_bypass_reservation():
             incoming_dates = []
@@ -714,7 +718,7 @@ class StockQuant(models.Model):
         quant = None
         if quants:
             # see _acquire_one_job for explanations
-            self._cr.execute("SELECT id FROM stock_quant WHERE id IN %s LIMIT 1 FOR NO KEY UPDATE SKIP LOCKED", [tuple(quants.ids)])
+            self._cr.execute("SELECT id FROM stock_quant WHERE id IN %s ORDER BY lot_id LIMIT 1 FOR NO KEY UPDATE SKIP LOCKED", [tuple(quants.ids)])
             stock_quant_result = self._cr.fetchone()
             if stock_quant_result:
                 quant = self.browse(stock_quant_result[0])
@@ -756,7 +760,7 @@ class StockQuant(models.Model):
 
         if float_compare(quantity, 0, precision_rounding=rounding) > 0:
             # if we want to reserve
-            available_quantity = self._get_available_quantity(product_id, location_id, lot_id=lot_id, package_id=package_id, owner_id=owner_id, strict=strict)
+            available_quantity = sum(quants.filtered(lambda q: float_compare(q.quantity, 0, precision_rounding=rounding) > 0).mapped('quantity')) - sum(quants.mapped('reserved_quantity'))
             if float_compare(quantity, available_quantity, precision_rounding=rounding) > 0:
                 raise UserError(_('It is not possible to reserve more products of %s than you have in stock.', product_id.display_name))
         elif float_compare(quantity, 0, precision_rounding=rounding) < 0:
diff --git a/addons/stock/tests/test_inventory.py b/addons/stock/tests/test_inventory.py
index 1c3defee8bd..f62dbf1fed2 100644
--- a/addons/stock/tests/test_inventory.py
+++ b/addons/stock/tests/test_inventory.py
@@ -155,10 +155,10 @@ class TestInventory(TransactionCase):
         stock_confirmation_wizard.action_confirm()
 
         # check
-        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product2, self.stock_location, lot_id=lot1, strict=True), 1.0)
+        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product2, self.stock_location, lot_id=lot1, strict=True), 11.0)
         self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product2, self.stock_location, strict=True), 10.0)
         self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product2, self.stock_location), 11.0)
-        self.assertEqual(len(self.env['stock.quant']._gather(self.product2, self.stock_location, lot_id=lot1, strict=True)), 1.0)
+        self.assertEqual(len(self.env['stock.quant']._gather(self.product2, self.stock_location, lot_id=lot1, strict=True).filtered(lambda q: q.lot_id)), 1.0)
         self.assertEqual(len(self.env['stock.quant']._gather(self.product2, self.stock_location, strict=True)), 1.0)
         self.assertEqual(len(self.env['stock.quant']._gather(self.product2, self.stock_location)), 2.0)
 
diff --git a/addons/stock/tests/test_move.py b/addons/stock/tests/test_move.py
index 6d344044aa4..1724c5d6480 100644
--- a/addons/stock/tests/test_move.py
+++ b/addons/stock/tests/test_move.py
@@ -354,10 +354,10 @@ class StockMove(TransactionCase):
 
         # no changes on quants, even if i made some move lines with a lot id whom reserved on untracked quants
         self.assertEqual(len(self.gather_relevant(self.product_serial, self.stock_location, strict=True)), 1.0)  # with a qty of 2
-        self.assertEqual(len(self.gather_relevant(self.product_serial, self.stock_location, lot_id=lot1, strict=True)), 1.0)
-        self.assertEqual(len(self.gather_relevant(self.product_serial, self.stock_location, lot_id=lot2, strict=True)), 1.0)
-        self.assertEqual(len(self.gather_relevant(self.product_serial, self.stock_location, lot_id=lot3, strict=True)), 0)
-        self.assertEqual(len(self.gather_relevant(self.product_serial, self.stock_location, lot_id=lot4, strict=True)), 0)
+        self.assertEqual(len(self.gather_relevant(self.product_serial, self.stock_location, lot_id=lot1, strict=True).filtered(lambda q: q.lot_id)), 1.0)
+        self.assertEqual(len(self.gather_relevant(self.product_serial, self.stock_location, lot_id=lot2, strict=True).filtered(lambda q: q.lot_id)), 1.0)
+        self.assertEqual(len(self.gather_relevant(self.product_serial, self.stock_location, lot_id=lot3, strict=True).filtered(lambda q: q.lot_id)), 0)
+        self.assertEqual(len(self.gather_relevant(self.product_serial, self.stock_location, lot_id=lot4, strict=True).filtered(lambda q: q.lot_id)), 0)
 
         move1.move_line_ids.write({'qty_done': 1.0})
 
@@ -667,7 +667,7 @@ class StockMove(TransactionCase):
         self.assertEqual(move1.reserved_availability, 0.0)
         self.assertEqual(len(move1.move_line_ids), 0)
         self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, strict=True), 1.0)
-        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, lot_id=lot1, strict=True), 1.0)
+        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, lot_id=lot1, strict=True), 2.0)
 
     def test_putaway_1(self):
         """ Receive products from a supplier. Check that putaway rules are rightly applied on
diff --git a/addons/stock/tests/test_quant.py b/addons/stock/tests/test_quant.py
index d00b31ff01d..b8e50473bf3 100644
--- a/addons/stock/tests/test_quant.py
+++ b/addons/stock/tests/test_quant.py
@@ -471,26 +471,26 @@ class StockQuant(TransactionCase):
 
         self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location), 2.0)
         self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, strict=True), 1.0)
-        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, lot_id=lot1), 1.0)
+        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, lot_id=lot1), 2.0)
 
         self.env['stock.quant']._update_reserved_quantity(self.product_serial, self.stock_location, 1.0, lot_id=lot1, strict=True)
 
         self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location), 1.0)
         self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, strict=True), 1.0)
-        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, lot_id=lot1), 0.0)
+        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, lot_id=lot1), 1.0)
 
         self.env['stock.quant']._update_reserved_quantity(self.product_serial, self.stock_location, -1.0, lot_id=lot1, strict=True)
 
         self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location), 2.0)
         self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, strict=True), 1.0)
-        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, lot_id=lot1), 1.0)
+        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, lot_id=lot1), 2.0)
 
         with self.assertRaises(UserError):
             self.env['stock.quant']._update_reserved_quantity(self.product_serial, self.stock_location, -1.0, strict=True)
 
         self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location), 2.0)
         self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, strict=True), 1.0)
-        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, lot_id=lot1), 1.0)
+        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product_serial, self.stock_location, lot_id=lot1), 2.0)
 
     def test_access_rights_1(self):
         """ Directly update the quant with a user with or without stock access rights should not raise
diff --git a/addons/stock/tests/test_stock_flow.py b/addons/stock/tests/test_stock_flow.py
index 1bdb886b85b..b299c19bc94 100644
--- a/addons/stock/tests/test_stock_flow.py
+++ b/addons/stock/tests/test_stock_flow.py
@@ -1124,7 +1124,7 @@ class TestStockFlow(TestStockCommon):
         self.assertEqual(lotproduct.qty_available, 10, "Wrong qty available for lotproduct")
         quants = self.StockQuantObj.search([('product_id', '=', lotproduct.id), ('location_id', '=', self.stock_location), ('lot_id', '=', lot1.id)])
         total_qty = sum([quant.quantity for quant in quants])
-        self.assertEqual(total_qty, 10, 'Expecting 0 units lot of lotproduct, but we got %.4f on location stock!' % (total_qty))
+        self.assertEqual(total_qty, 10, 'Expecting 10 units lot of lotproduct, but we got %.4f on location stock!' % (total_qty))
         quants = self.StockQuantObj.search([('product_id', '=', lotproduct.id), ('location_id', '=', self.stock_location), ('lot_id', '=', False)])
         total_qty = sum([quant.quantity for quant in quants])
         self.assertEqual(total_qty, 0, 'Expecting 0 units lot of lotproduct, but we got %.4f on location stock!' % (total_qty))