diff --git a/erpnext/assets/doctype/asset_maintenance/asset_maintenance.js b/erpnext/assets/doctype/asset_maintenance/asset_maintenance.js
index 3c135d4..001fc26 100644
--- a/erpnext/assets/doctype/asset_maintenance/asset_maintenance.js
+++ b/erpnext/assets/doctype/asset_maintenance/asset_maintenance.js
@@ -24,26 +24,6 @@
 				return indicator;
 			}
 		);
-
-		frm.set_query('select_serial_no', function(doc){
-			return {
-				asset: frm.doc.asset_name
-			}
-		})
-	},
-
-	select_serial_no: (frm) => {
-		let serial_nos = frm.doc.serial_no || frm.doc.select_serial_no;
-		if (serial_nos) {
-			serial_nos = serial_nos.split('\n');
-			serial_nos.push(frm.doc.select_serial_no);
-
-			const unique_sn = serial_nos.filter(function(elem, index, self) {
-			    return index === self.indexOf(elem);
-			});
-
-			frm.set_value("serial_no", unique_sn.join('\n'));
-		}
 	},
 
 	refresh: (frm) => {
@@ -93,25 +73,6 @@
 	},
 	end_date: (frm, cdt, cdn)  => {
 		get_next_due_date(frm, cdt, cdn);
-	},
-	assign_to: (frm, cdt, cdn)  => {
-		var d = locals[cdt][cdn];
-		if (frm.doc.__islocal) {
-			frappe.model.set_value(cdt, cdn, "assign_to", "");
-			frappe.model.set_value(cdt, cdn, "assign_to_name", "");
-			frappe.throw(__("Please save before assigning task."));
-		}
-		if (d.assign_to) {
-			return frappe.call({
-				method: 'erpnext.assets.doctype.asset_maintenance.asset_maintenance.assign_tasks',
-				args: {
-					asset_maintenance_name: frm.doc.name,
-					assign_to_member: d.assign_to,
-					maintenance_task: d.maintenance_task,
-					next_due_date: d.next_due_date
-				}
-			});
-		}
 	}
 });
 
diff --git a/erpnext/assets/doctype/asset_maintenance/asset_maintenance.py b/erpnext/assets/doctype/asset_maintenance/asset_maintenance.py
index ecb55dd..3f04611 100644
--- a/erpnext/assets/doctype/asset_maintenance/asset_maintenance.py
+++ b/erpnext/assets/doctype/asset_maintenance/asset_maintenance.py
@@ -16,12 +16,11 @@
 				throw(_("Start date should be less than end date for task {0}").format(task.maintenance_task))
 			if getdate(task.next_due_date) < getdate(nowdate()):
 				task.maintenance_status = "Overdue"
+			if not task.assign_to and self.docstatus == 0:
+				throw(_("Row #{}: Please asign task to a member.").format(task.idx))
 
 	def on_update(self):
 		for task in self.get('asset_maintenance_tasks'):
-			if not task.assign_to:
-				task.db_set("assign_to", self.maintenance_manager)
-				task.db_set("assign_to_name", self.maintenance_manager_name)
 			assign_tasks(self.name, task.assign_to, task.maintenance_task, task.next_due_date)
 		self.sync_maintenance_tasks()
 
@@ -108,7 +107,7 @@
 
 @frappe.whitelist()
 def get_team_members(doctype, txt, searchfield, start, page_len, filters):
-	return frappe.db.get_values('Maintenance Team Member', {'parent':filters.get("maintenance_team")})
+	return frappe.db.get_values('Maintenance Team Member', { 'parent': filters.get("maintenance_team") })
 
 @frappe.whitelist()
 def get_maintenance_log(asset_name):
diff --git a/erpnext/assets/doctype/asset_maintenance/test_asset_maintenance.py b/erpnext/assets/doctype/asset_maintenance/test_asset_maintenance.py
index 6c2fd67..392fbdd 100644
--- a/erpnext/assets/doctype/asset_maintenance/test_asset_maintenance.py
+++ b/erpnext/assets/doctype/asset_maintenance/test_asset_maintenance.py
@@ -125,13 +125,15 @@
 			"start_date": nowdate(),
 			"periodicity": "Monthly",
 			"maintenance_type": "Preventive Maintenance",
-			"maintenance_status": "Planned"
+			"maintenance_status": "Planned",
+			"assign_to": "marcus@abc.com"
 			},
 			{"maintenance_task": "Check Gears",
 			"start_date": nowdate(),
 			"periodicity": "Yearly",
 			"maintenance_type": "Calibration",
-			"maintenance_status": "Planned"
+			"maintenance_status": "Planned",
+			"assign_to": "thalia@abc.com"
 			}
 		]