Uploading MQTT GW Sketch fails with avrdude error

[dakky]

Hello

ich just downloaded the 1.5 release of mysensors to restart the project after some break

I configured MyConfig.h, loaded the example sketch and configured MyMQTT.h and the sketch compiles successfully. But when trying to upload the sketch i receive the folowing error:

Sketch uses 31,688 bytes (98%) of program storage space. Maximum is 32,256 bytes.
Global variables use 1,015 bytes (49%) of dynamic memory, leaving 1,033 bytes for local variables. Maximum is 2,048 bytes.
avrdude: verification error, first mismatch at byte 0x7800
         0xff != 0x35
avrdude: verification error; content mismatch

This happens ONLY with this sketch. The sample arduino blink works fine. Any idea whats wrong?
I use the arduino UnO R3 as gateway

[dakky]

Hurm strange things are happening here ...

short timeline:

• did some googeling
• most reasonable result: sketch is too big and conflicts with bootloader
• tried to reburn bootloader via usbtinyisp and arduino software
• can't upload anything to the arduino:
  avrdude: stk500_recv(): programmer is not responding
  Oh NO, Not again!
• got certainty, that this error results from "corrupt" bootloader (I already "lost" an uno with this problem)
• tried to burn the bootloader via avrdude:
  I used the config file from th arduino software AND the .hex file from the arduino software
• result: can upload again AND the mqtt sketch works too

I don't have to understand that, have I ?