diff --git a/PrinterConnection.py b/PrinterConnection.py
index d94beea6c5..ff5e97584d 100644
--- a/PrinterConnection.py
+++ b/PrinterConnection.py
@@ -117,7 +117,6 @@ class PrinterConnection(SignalEmitter):
             self._connect_thread.start()
 
     def updateFirmware(self, file_name):
-        print("Update firmware; " , self._is_connecting, " ", self._is_connected )
         if self._is_connecting or  self._is_connected:
             self.close()
         hex_file = intelHex.readHex(file_name)
@@ -219,9 +218,13 @@ class PrinterConnection(SignalEmitter):
     
     ##  Close the printer connection    
     def close(self):
+        if self._connect_thread.isAlive():
+            self._connect_thread.join()
         if self._serial is not None:
-            self._serial.close()
             self.setIsConnected(False)
+            self._listen_thread.join()
+            self._serial.close()
+            
         self._serial = None
     
     def isConnected(self):
@@ -417,8 +420,8 @@ class PrinterConnection(SignalEmitter):
             return None
         try:
             ret = self._serial.readline()
-        except:
-            Logger.log('e',"Unexpected error while reading serial port.")
+        except Exception as e:
+            Logger.log('e',"Unexpected error while reading serial port. %s" %e)
             self._setErrorState("Printer has been disconnected") 
             #self._errorValue = getExceptionString()
             self.close()
diff --git a/avr_isp/stk500v2.py b/avr_isp/stk500v2.py
index 778adc7da3..f4c352f977 100644
--- a/avr_isp/stk500v2.py
+++ b/avr_isp/stk500v2.py
@@ -76,18 +76,18 @@ class Stk500v2(ispBase.IspBase):
         recv = self.sendMessage([0x1D, 4, 4, 0, data[0], data[1], data[2], data[3]])
         return recv[2:6]
     
-    def writeFlash(self, flashData):
+    def writeFlash(self, flash_data):
         #Set load addr to 0, in case we have more then 64k flash we need to enable the address extension
-        pageSize = self.chip['pageSize'] * 2
-        flashSize = pageSize * self.chip['pageCount']
+        page_size = self.chip['pageSize'] * 2
+        flashSize = page_size * self.chip['pageCount']
         if flashSize > 0xFFFF:
             self.sendMessage([0x06, 0x80, 0x00, 0x00, 0x00])
         else:
             self.sendMessage([0x06, 0x00, 0x00, 0x00, 0x00])
         
-        loadCount = (len(flashData) + pageSize - 1) / pageSize
+        loadCount = (len(flash_data) + page_size - 1) / page_size
         for i in range(0, loadCount):
-            recv = self.sendMessage([0x13, pageSize >> 8, pageSize & 0xFF, 0xc1, 0x0a, 0x40, 0x4c, 0x20, 0x00, 0x00] + flashData[(i * pageSize):(i * pageSize + pageSize)])
+            recv = self.sendMessage([0x13, page_size >> 8, page_size & 0xFF, 0xc1, 0x0a, 0x40, 0x4c, 0x20, 0x00, 0x00] + flash_data[(i * page_size):(i * page_size + page_size)])
             if self.progressCallback is not None:
                 if self._has_checksum:
                     self.progressCallback(i + 1, loadCount)