Did you get such error?
Another user reported such issue:
My last recommendation would be to make sure that there is no special character and to store the images next to the *.p4d file.
However several users have reported such behavior, including my self.
I have raised the issue to our developers. There might be something wrong with Pix4Dmapper.
For now, I would recommend you to try my last recommendations.
And I will keep you updated if we can find what’s wrong there.
Thank you
Best