diff --git a/client-barcode/freitagskasse.py b/client-barcode/freitagskasse.py
index 7552c48..d0995bc 100644
--- a/client-barcode/freitagskasse.py
+++ b/client-barcode/freitagskasse.py
@@ -12,6 +12,7 @@ import sys
 from decimal import Decimal
 import os
 import time
+import urllib2
 
 
 def clear():
@@ -100,27 +101,36 @@ class Status:
 
 	def login(self, auth_blob):
 		assert(not self.logged_in())
+
 		user_name = net.get_user_name_from_auth_blob(auth_blob)
+		balance = net.get_balance(user_name)
+
 		self.auth_blob = auth_blob
 		self.login_name = user_name
-		self.balance = net.get_balance(user_name)
+		self.balance = balance
 		self.transfers = list()
 
 	def commit(self):
 		assert(self.logged_in())
 
 		# Process command queue
-		for (command, balance_backup) in self.transfers:
-			command.run(self.login_name)
-		self.transfers = None
+		for (command, balance_backup) in list(self.transfers):
+			try:
+				command.run(self.login_name)
+			except urllib2.HTTPError as e:
+				error_page('FEHLER bei Kommunikation mit Server "%s"' % str(e))
+				break
+			else:
+				self.transfers.pop(0)
 
-		# Show final balance for some time
-		clear()
-		self.dump()
-		delay('Logout', 3)
+		if not self.transfers:
+			# Show final balance for some time
+			clear()
+			self.dump()
+			delay('Logout', 3)
 
-		# Logout
-		self._reset()
+			# Logout
+			self._reset()
 
 	def find(self, item_id):
 		try:
@@ -171,12 +181,18 @@ def handle(line, status):
 			item_id = int(line)  # TODO
 			try:
 				item = status.find(item_id)
-			except:  # TODO
-				error_page('FEHLER: Aktion oder Ware "%s" nicht bekannt' % line)
+			except urllib2.HTTPError as e:
+				if e.code == 404:  # URL not found == item not found with REST
+					error_page('FEHLER: Aktion oder Ware "%s" nicht bekannt' % line)
+				else:
+					error_page('FEHLER bei Kommunikation mit Server "%s"' % str(e))
 			else:
 				status.buy(item)
 	else:
-		status.login(line)
+		try:
+			status.login(line)
+		except urllib2.URLError as e:
+			error_page('FEHLER bei Kommunikation mit Server "%s"' % e.reason)
 
 
 def main():