Error after updating Arduino AVR boards from v1.6.20 to v1.6.21

today (10-April-2018) I updated Arduino AVR Boards version 1.6.21 using Board Manager.
After that I got for my Arduino Nano and Arduino UNO following message after compiling an sketch and before loading:

avrdude: can't open config file "C:\Users\Albnar\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino9/etc/avrdude.conf": No such file or directory

The avrdude.conf was deleted during update!
I got a new avrdude.conf from

Now I get another error:
avrdude: Can't find programmer id "arduino"

I tried to reinstall the version 1.6.20 it does not work anymore. The error is the same: avrdude: Can't find programmer id "arduino".
What can I do?
Best regards

It's frustrating because usually Boards Manager works fine but every so often it glitches and it's not designed well to gracefully recover from this.

Try this:

  • Close all Arduino IDE windows.
  • Delete C:\Users\Albnar\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino9. Please be very careful when deleting things from your computer. When in doubt back up!
  • Start the Arduino IDE.
  • Try uploading again.

Deleting the incompletely installed avrdude will force the Arduino IDE to use the version of the tool which comes with the Arduino IDE, as it was doing before you updated to Arduino AVR Boards 1.6.21.

I got a new avrdude.conf from

That avrdude.conf is specifically for the ATtiny85-based Gemma board so it is not necessarily a direct replacement for the file that was not installed during the problematic update.