diff --git a/frappe/core/doctype/user_permission/user_permission.json b/frappe/core/doctype/user_permission/user_permission.json
index 9a38f8d953..c2ea05e731 100644
--- a/frappe/core/doctype/user_permission/user_permission.json
+++ b/frappe/core/doctype/user_permission/user_permission.json
@@ -41,7 +41,7 @@
    "remember_last_selected_value": 0,
    "report_hide": 0,
    "reqd": 1,
-   "search_index": 0,
+   "search_index": 1,
    "set_only_once": 0,
    "translatable": 0,
    "unique": 0
@@ -222,7 +222,7 @@
  "issingle": 0,
  "istable": 0,
  "max_attachments": 0,
- "modified": "2018-11-12 16:26:12.362352",
+ "modified": "2019-02-13 22:58:27.428741",
  "modified_by": "Administrator",
  "module": "Core",
  "name": "User Permission",
diff --git a/frappe/database.py b/frappe/database.py
index d9ad3e7cbe..10a51af24e 100644
--- a/frappe/database.py
+++ b/frappe/database.py
@@ -967,9 +967,14 @@ class Database:
 
 	def get_descendants(self, doctype, name):
 		'''Return descendants of the current record'''
-		lft, rgt = self.get_value(doctype, name, ('lft', 'rgt'))
-		return self.sql_list('''select name from `tab{doctype}`
-			where lft > {lft} and rgt < {rgt}'''.format(doctype=doctype, lft=lft, rgt=rgt))
+		node_location_indexes = self.get_value(doctype, name, ('lft', 'rgt'))
+		if node_location_indexes:
+			lft, rgt = node_location_indexes
+			return self.sql_list('''select name from `tab{doctype}`
+				where lft > {lft} and rgt < {rgt}'''.format(doctype=doctype, lft=lft, rgt=rgt))
+		else:
+			# when document does not exist
+			return []
 
 def enqueue_jobs_after_commit():
 	if frappe.flags.enqueue_after_commit and len(frappe.flags.enqueue_after_commit) > 0: