diff --git a/klippy/console.py b/klippy/console.py
index 4d68b8de..1645a0be 100755
--- a/klippy/console.py
+++ b/klippy/console.py
@@ -78,7 +78,7 @@ class KeyboardReader:
                 return None
         try:
             msg = self.ser.msgparser.create_command(line)
-        except msgproto.error, e:
+        except msgproto.error as e:
             self.output("Error: %s" % (str(e),))
             return None
         return msg
diff --git a/klippy/gcode.py b/klippy/gcode.py
index 6709e26f..c6f7248b 100644
--- a/klippy/gcode.py
+++ b/klippy/gcode.py
@@ -107,7 +107,7 @@ class GCodeParser:
             handler = self.gcode_handlers.get(cmd, self.cmd_default)
             try:
                 handler(params)
-            except error, e:
+            except error as e:
                 self.respond_error(str(e))
             except:
                 logging.exception("Exception in command handler")
@@ -224,7 +224,7 @@ class GCodeParser:
         print_time = self.toolhead.get_last_move_time()
         try:
             heater.set_temp(print_time, temp)
-        except heater.error, e:
+        except heater.error as e:
             self.respond_error(str(e))
             return
         if wait:
@@ -264,7 +264,7 @@ class GCodeParser:
         self.process_commands(deactivate_gcode.split('\n'), need_ack=False)
         try:
             self.toolhead.set_extruder(e)
-        except homing.EndstopError, e:
+        except homing.EndstopError as e:
             self.respond_error(str(e))
             return
         self.extruder = e
@@ -296,12 +296,12 @@ class GCodeParser:
                 if speed <= 0.:
                     raise ValueError()
                 self.speed = speed
-        except ValueError, e:
+        except ValueError as e:
             self.last_position = self.toolhead.get_position()
             raise error("Unable to parse move '%s'" % (params['#original'],))
         try:
             self.toolhead.move(self.last_position, self.speed)
-        except homing.EndstopError, e:
+        except homing.EndstopError as e:
             self.respond_error(str(e))
             self.last_position = self.toolhead.get_position()
     def cmd_G4(self, params):
@@ -327,7 +327,7 @@ class GCodeParser:
             homing_state.set_no_verify_retract()
         try:
             self.toolhead.home(homing_state)
-        except homing.EndstopError, e:
+        except homing.EndstopError as e:
             self.toolhead.motor_off()
             self.respond_error(str(e))
             return
@@ -424,7 +424,7 @@ class GCodeParser:
             return
         try:
             res = self.toolhead.query_endstops()
-        except self.printer.mcu.error, e:
+        except self.printer.mcu.error as e:
             self.respond_error(str(e))
             return
         self.respond(" ".join(["%s:%s" % (name, ["open", "TRIGGERED"][not not t])
diff --git a/klippy/homing.py b/klippy/homing.py
index 1e06f0b9..7d4cfb5b 100644
--- a/klippy/homing.py
+++ b/klippy/homing.py
@@ -43,7 +43,7 @@ class Homing:
         for s, es, last_pos in endstops:
             try:
                 es.home_wait()
-            except es.error, e:
+            except es.error as e:
                 raise EndstopError("Failed to home stepper %s: %s" % (
                     s.name, str(e)))
             post_home_pos = s.mcu_stepper.get_mcu_position()
diff --git a/klippy/klippy.py b/klippy/klippy.py
index ba5d1762..0cfd79e9 100644
--- a/klippy/klippy.py
+++ b/klippy/klippy.py
@@ -61,7 +61,7 @@ class ConfigWrapper:
             (self.section.lower(), option.lower())] = 1
         try:
             v = parser(self.section, option)
-        except self.error, e:
+        except self.error as e:
             raise
         except:
             raise self.error("Unable to parse option '%s' in section '%s'" % (
@@ -199,15 +199,15 @@ class Printer:
             self.mcu.connect()
             self.gcode.set_printer_ready(True)
             self.state_message = message_ready
-        except ConfigParser.Error, e:
+        except ConfigParser.Error as e:
             logging.exception("Config error")
             self.state_message = "%s%s" % (str(e), message_restart)
             self.reactor.update_timer(self.stats_timer, self.reactor.NEVER)
-        except msgproto.error, e:
+        except msgproto.error as e:
             logging.exception("Protocol error")
             self.state_message = "%s%s" % (str(e), message_protocol_error)
             self.reactor.update_timer(self.stats_timer, self.reactor.NEVER)
-        except mcu.error, e:
+        except mcu.error as e:
             logging.exception("MCU error during connect")
             self.state_message = "%s%s" % (str(e), message_mcu_connect_error)
             self.reactor.update_timer(self.stats_timer, self.reactor.NEVER)
diff --git a/klippy/mcu.py b/klippy/mcu.py
index 5d63af72..e22f6bb6 100644
--- a/klippy/mcu.py
+++ b/klippy/mcu.py
@@ -457,7 +457,7 @@ class MCU:
         self._emergency_stop_cmd = self.lookup_command("emergency_stop")
         try:
             self._reset_cmd = self.lookup_command("reset")
-        except self.serial.msgparser.error, e:
+        except self.serial.msgparser.error as e:
             pass
         self.register_msg(self.handle_shutdown, 'shutdown')
         self.register_msg(self.handle_shutdown, 'is_shutdown')
diff --git a/klippy/serialhdl.py b/klippy/serialhdl.py
index d6179a4b..8b99cf25 100644
--- a/klippy/serialhdl.py
+++ b/klippy/serialhdl.py
@@ -69,7 +69,7 @@ class SerialReader:
                         self.serialport, self.baud, timeout=0)
                 else:
                     self.ser = open(self.serialport, 'rb+')
-            except (OSError, serial.SerialException), e:
+            except (OSError, serial.SerialException) as e:
                 logging.warn("Unable to open port: %s" % (e,))
                 self.reactor.pause(starttime + 5.)
                 continue