I tried to restart the install using the alternate CD. I had with the debian installer the same message that the ubiquity installer displayed just after the partitionning.
Here it is: "No NewWorld startup partition was found. The yaboot bootloader need a partition <<Apple_Bootstrap>> with a size greater than 819000 bytes and using a Macintosh HFS filesystem." -- installer crash - yaboot could not find a hfs bootstrap partition with enough space https://launchpad.net/bugs/58432 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
