diff --git a/erpnext/patches.txt b/erpnext/patches.txt
index 704b6696db1..b5ee1a4ce8c 100644
--- a/erpnext/patches.txt
+++ b/erpnext/patches.txt
@@ -1,4 +1,5 @@
 erpnext.patches.v12_0.update_is_cancelled_field
+erpnext.patches.v13_0.add_bin_unique_constraint
 erpnext.patches.v11_0.rename_production_order_to_work_order
 erpnext.patches.v11_0.refactor_naming_series
 erpnext.patches.v11_0.refactor_autoname_naming
diff --git a/erpnext/patches/v13_0/add_bin_unique_constraint.py b/erpnext/patches/v13_0/add_bin_unique_constraint.py
new file mode 100644
index 00000000000..57fbaae9d8d
--- /dev/null
+++ b/erpnext/patches/v13_0/add_bin_unique_constraint.py
@@ -0,0 +1,63 @@
+import frappe
+
+from erpnext.stock.stock_balance import (
+	get_balance_qty_from_sle,
+	get_indented_qty,
+	get_ordered_qty,
+	get_planned_qty,
+	get_reserved_qty,
+)
+from erpnext.stock.utils import get_bin
+
+
+def execute():
+	delete_broken_bins()
+	delete_and_patch_duplicate_bins()
+
+def delete_broken_bins():
+	# delete useless bins
+	frappe.db.sql("delete from `tabBin` where item_code is null or warehouse is null")
+
+def delete_and_patch_duplicate_bins():
+
+	duplicate_bins = frappe.db.sql("""
+		SELECT
+			item_code, warehouse, count(*) as bin_count
+		FROM
+			tabBin
+		GROUP BY
+			item_code, warehouse
+		HAVING
+			bin_count > 1
+	""", as_dict=1)
+
+	for duplicate_bin in duplicate_bins:
+		item_code = duplicate_bin.item_code
+		warehouse = duplicate_bin.warehouse
+		existing_bins = frappe.get_list("Bin",
+				filters={
+					"item_code": item_code,
+					"warehouse": warehouse
+					},
+				fields=["name"],
+				order_by="creation",)
+
+		# keep last one
+		existing_bins.pop()
+
+		for broken_bin in existing_bins:
+			frappe.delete_doc("Bin", broken_bin.name)
+
+		qty_dict = {
+			"reserved_qty": get_reserved_qty(item_code, warehouse),
+			"indented_qty": get_indented_qty(item_code, warehouse),
+			"ordered_qty": get_ordered_qty(item_code, warehouse),
+			"planned_qty": get_planned_qty(item_code, warehouse),
+			"actual_qty": get_balance_qty_from_sle(item_code, warehouse)
+		}
+
+		bin = get_bin(item_code, warehouse)
+		bin.update(qty_dict)
+		bin.update_reserved_qty_for_production()
+		bin.update_reserved_qty_for_sub_contracting()
+		bin.db_update()
diff --git a/erpnext/stock/doctype/bin/bin.json b/erpnext/stock/doctype/bin/bin.json
index 8e79f0e5552..56dc71c57e1 100644
--- a/erpnext/stock/doctype/bin/bin.json
+++ b/erpnext/stock/doctype/bin/bin.json
@@ -33,6 +33,7 @@
    "oldfieldtype": "Link",
    "options": "Warehouse",
    "read_only": 1,
+   "reqd": 1,
    "search_index": 1
   },
   {
@@ -46,6 +47,7 @@
    "oldfieldtype": "Link",
    "options": "Item",
    "read_only": 1,
+   "reqd": 1,
    "search_index": 1
   },
   {
@@ -169,10 +171,11 @@
  "idx": 1,
  "in_create": 1,
  "links": [],
- "modified": "2021-03-30 23:09:39.572776",
+ "modified": "2022-01-30 17:04:54.715288",
  "modified_by": "Administrator",
  "module": "Stock",
  "name": "Bin",
+ "naming_rule": "Expression (old style)",
  "owner": "Administrator",
  "permissions": [
   {
@@ -200,5 +203,6 @@
  "quick_entry": 1,
  "search_fields": "item_code,warehouse",
  "sort_field": "modified",
- "sort_order": "ASC"
+ "sort_order": "ASC",
+ "states": []
 }
\ No newline at end of file
diff --git a/erpnext/stock/doctype/bin/bin.py b/erpnext/stock/doctype/bin/bin.py
index 11ff359b483..1d874cd06fb 100644
--- a/erpnext/stock/doctype/bin/bin.py
+++ b/erpnext/stock/doctype/bin/bin.py
@@ -96,7 +96,7 @@ class Bin(Document):
 		self.db_set('projected_qty', self.projected_qty)
 
 def on_doctype_update():
-	frappe.db.add_index("Bin", ["item_code", "warehouse"])
+	frappe.db.add_unique("Bin", ["item_code", "warehouse"], constraint_name="unique_item_warehouse")
 
 
 def update_stock(bin_name, args, allow_negative_stock=False, via_landed_cost_voucher=False):
diff --git a/erpnext/stock/doctype/bin/test_bin.py b/erpnext/stock/doctype/bin/test_bin.py
index 9c390d94b4e..250126c6b98 100644
--- a/erpnext/stock/doctype/bin/test_bin.py
+++ b/erpnext/stock/doctype/bin/test_bin.py
@@ -1,9 +1,36 @@
 # Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
 # See license.txt
 
-import unittest
+import frappe
 
-# test_records = frappe.get_test_records('Bin')
+from erpnext.stock.doctype.item.test_item import make_item
+from erpnext.stock.utils import _create_bin
+from erpnext.tests.utils import ERPNextTestCase
 
-class TestBin(unittest.TestCase):
-	pass
+
+class TestBin(ERPNextTestCase):
+
+
+	def test_concurrent_inserts(self):
+		""" Ensure no duplicates are possible in case of concurrent inserts"""
+		item_code = "_TestConcurrentBin"
+		make_item(item_code)
+		warehouse = "_Test Warehouse - _TC"
+
+		bin1 = frappe.get_doc(doctype="Bin", item_code=item_code, warehouse=warehouse)
+		bin1.insert()
+
+		bin2 = frappe.get_doc(doctype="Bin", item_code=item_code, warehouse=warehouse)
+		with self.assertRaises(frappe.UniqueValidationError):
+			bin2.insert()
+
+		# util method should handle it
+		bin = _create_bin(item_code, warehouse)
+		self.assertEqual(bin.item_code, item_code)
+
+		frappe.db.rollback()
+
+	def test_index_exists(self):
+		indexes = frappe.db.sql("show index from tabBin where Non_unique = 0", as_dict=1)
+		if not any(index.get("Key_name") == "unique_item_warehouse" for index in indexes):
+			self.fail(f"Expected unique index on item-warehouse")
diff --git a/erpnext/stock/doctype/stock_entry/stock_entry.py b/erpnext/stock/doctype/stock_entry/stock_entry.py
index ab106e036f1..a5bf2397411 100644
--- a/erpnext/stock/doctype/stock_entry/stock_entry.py
+++ b/erpnext/stock/doctype/stock_entry/stock_entry.py
@@ -1674,6 +1674,8 @@ class StockEntry(StockController):
 			for d in self.get("items"):
 				item_code = d.get('original_item') or d.get('item_code')
 				reserve_warehouse = item_wh.get(item_code)
+				if not (reserve_warehouse and item_code):
+					continue
 				stock_bin = get_bin(item_code, reserve_warehouse)
 				stock_bin.update_reserved_qty_for_sub_contracting()
 
diff --git a/erpnext/stock/utils.py b/erpnext/stock/utils.py
index 4d77367a051..b8bdf39301e 100644
--- a/erpnext/stock/utils.py
+++ b/erpnext/stock/utils.py
@@ -177,13 +177,7 @@ def get_latest_stock_balance():
 def get_bin(item_code, warehouse):
 	bin = frappe.db.get_value("Bin", {"item_code": item_code, "warehouse": warehouse})
 	if not bin:
-		bin_obj = frappe.get_doc({
-			"doctype": "Bin",
-			"item_code": item_code,
-			"warehouse": warehouse,
-		})
-		bin_obj.flags.ignore_permissions = 1
-		bin_obj.insert()
+		bin_obj = _create_bin(item_code, warehouse)
 	else:
 		bin_obj = frappe.get_doc('Bin', bin, for_update=True)
 	bin_obj.flags.ignore_permissions = True
@@ -193,16 +187,24 @@ def get_or_make_bin(item_code: str , warehouse: str) -> str:
 	bin_record = frappe.db.get_value('Bin', {'item_code': item_code, 'warehouse': warehouse})
 
 	if not bin_record:
-		bin_obj = frappe.get_doc({
-			"doctype": "Bin",
-			"item_code": item_code,
-			"warehouse": warehouse,
-		})
+		bin_obj = _create_bin(item_code, warehouse)
+		bin_record = bin_obj.name
+	return bin_record
+
+def _create_bin(item_code, warehouse):
+	"""Create a bin and take care of concurrent inserts."""
+
+	bin_creation_savepoint = "create_bin"
+	try:
+		frappe.db.savepoint(bin_creation_savepoint)
+		bin_obj = frappe.get_doc(doctype="Bin", item_code=item_code, warehouse=warehouse)
 		bin_obj.flags.ignore_permissions = 1
 		bin_obj.insert()
-		bin_record = bin_obj.name
+	except frappe.UniqueValidationError:
+		frappe.db.rollback(save_point=bin_creation_savepoint)  # preserve transaction in postgres
+		bin_obj = frappe.get_last_doc("Bin", {"item_code": item_code, "warehouse": warehouse})
 
-	return bin_record
+	return bin_obj
 
 def update_bin(args, allow_negative_stock=False, via_landed_cost_voucher=False):
 	"""WARNING: This function is deprecated. Inline this function instead of using it."""