Overview of the sixth dialog system technology challenge: DSTC6.

•DSTC6: Dialog Challenge to improve performance of end-to-end dialog systems using Neural Network models and dialog breakdown detection.•Track 1, End-to-End Goal Oriented Dialog Learning: selection of the best system response. Hybrid Code Network and Memory Network were the best models.•Track 2, End-to-End Conversation Modeling: system response generation. 78.5% of the automatically generated sentences were rated as acceptable responses by humans.•Track 3, Dialogue Breakdown Detection. The submitted systems performed as well as humans in detecting dialog breakdown, for both English and Japanese data-sets.