diff --git a/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py b/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py
index 21b0885..80aa73a 100644
--- a/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py
+++ b/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py
@@ -123,7 +123,6 @@
 				stopped = frappe.db.sql("select name from `tabPurchase Order` where status = 'Stopped' and name = %s", d.purchase_order)
 				if stopped:
 					throw(_("Purchase Order {0} is 'Stopped'").format(d.purchase_order))
-					raise Exception
 
 	def validate_with_previous_doc(self):
 		super(PurchaseInvoice, self).validate_with_previous_doc(self.tname, {
@@ -168,8 +167,7 @@
 		if self.is_opening != 'Yes':
 			self.aging_date = self.posting_date
 		elif not self.aging_date:
-			msgprint(_("Ageing date is mandatory for opening entry"))
-			raise Exception
+			throw(_("Ageing date is mandatory for opening entry"))
 
 	def set_against_expense_account(self):
 		auto_accounting_for_stock = cint(frappe.defaults.get_global_default("auto_accounting_for_stock"))
@@ -210,7 +208,6 @@
 			 for d in self.get('entries'):
 				 if not d.purchase_receipt:
 					 throw(_("Purchase Receipt number required for Item {0}").format(d.item_code))
-					 raise Exception
 
 	def validate_write_off_account(self):
 		if self.write_off_amount and not self.write_off_account:
diff --git a/erpnext/accounts/doctype/sales_invoice/sales_invoice.py b/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
index b5bf73f..b40722c 100644
--- a/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
+++ b/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
@@ -301,9 +301,7 @@
 		if self.is_opening != 'Yes':
 			self.aging_date = self.posting_date
 		elif not self.aging_date:
-			msgprint(_("Ageing Date is mandatory for opening entry"))
-			raise Exception
-
+			throw(_("Ageing Date is mandatory for opening entry"))
 
 	def set_against_income_account(self):
 		"""Set against account for debit to account"""
@@ -336,8 +334,7 @@
 				where name = %s and (customer = %s or
 					ifnull(customer,'')='')""", (self.project_name, self.customer))
 			if not res:
-				msgprint(_("Customer {0} does not belong to project {1}").format(self.customer,self.project_name))
-				raise Exception
+				throw(_("Customer {0} does not belong to project {1}").format(self.customer,self.project_name))
 
 	def validate_pos(self):
 		if not self.cash_bank_account and flt(self.paid_amount):
@@ -440,8 +437,7 @@
 				submitted = frappe.db.sql("""select name from `tabDelivery Note`
 					where docstatus = 1 and name = %s""", d.delivery_note)
 				if not submitted:
-					msgprint(_("Delivery Note {0} is not submitted").format(d.delivery_note))
-					raise Exception
+					throw(_("Delivery Note {0} is not submitted").format(d.delivery_note))
 
 	def update_stock_ledger(self):
 		sl_entries = []
diff --git a/erpnext/buying/doctype/purchase_order/purchase_order.py b/erpnext/buying/doctype/purchase_order/purchase_order.py
index 02170ff..a83debc 100644
--- a/erpnext/buying/doctype/purchase_order/purchase_order.py
+++ b/erpnext/buying/doctype/purchase_order/purchase_order.py
@@ -168,8 +168,7 @@
 			where t1.name = t2.parent and t2.purchase_order = %s and t1.docstatus = 1""",
 			self.name)
 		if submitted:
-			msgprint(_("Purchase Invoice {0} is already submitted").format(", ".join(submitted)))
-			raise Exception
+			throw(_("Purchase Invoice {0} is already submitted").format(", ".join(submitted)))
 
 		frappe.db.set(self,'status','Cancelled')
 		self.update_prevdoc_status()
diff --git a/erpnext/hr/doctype/leave_application/leave_application.py b/erpnext/hr/doctype/leave_application/leave_application.py
index f7084ef..d74e930 100755
--- a/erpnext/hr/doctype/leave_application/leave_application.py
+++ b/erpnext/hr/doctype/leave_application/leave_application.py
@@ -71,8 +71,8 @@
 
 		if block_dates:
 			if self.status == "Approved":
-				frappe.msgprint(_("Cannot approve leave as you are not authorized to approve leaves on Block Dates"))
-				raise LeaveDayBlockedError
+				frappe.throw(_("Cannot approve leave as you are not authorized to approve leaves on Block Dates"),
+					LeaveDayBlockedError)
 
 	def get_holidays(self):
 		tot_hol = frappe.db.sql("""select count(*) from `tabHoliday` h1, `tabHoliday List` h2, `tabEmployee` e1
diff --git a/erpnext/selling/doctype/opportunity/opportunity.py b/erpnext/selling/doctype/opportunity/opportunity.py
index 9ba6e56..41b42ea 100644
--- a/erpnext/selling/doctype/opportunity/opportunity.py
+++ b/erpnext/selling/doctype/opportunity/opportunity.py
@@ -49,8 +49,7 @@
 
 			return ret
 		else:
-			msgprint("Customer : %s does not exist in system." % (name))
-			raise Exception
+			frappe.throw(_("Customer {0} does not exist").format(name), frappe.DoesNotExistError)
 
 	def on_update(self):
 		self.add_calendar_event()
diff --git a/erpnext/setup/doctype/authorization_control/authorization_control.py b/erpnext/setup/doctype/authorization_control/authorization_control.py
index 25d2de0..03c187b 100644
--- a/erpnext/setup/doctype/authorization_control/authorization_control.py
+++ b/erpnext/setup/doctype/authorization_control/authorization_control.py
@@ -35,7 +35,6 @@
 			if not has_common(appr_roles, frappe.user.get_roles()) and not has_common(appr_users, [session['user']]):
 				frappe.msgprint(_("Not authroized since {0} exceeds limits").format(_(based_on)))
 				frappe.throw(_("Can be approved by {0}").format(comma_or(appr_roles + appr_users)))
-				raise Exception
 
 
 	# Check if authorization rule is set specific to user