I hit a problem with doing a preseeded Ubuntu installation, where the partitioning wouldn’t continue without a confirmation.

I found lots of discussions about how to work round the problem with the "write the changes to disks and configure lvm" message, but I could have fixed the problems with a lot less trial and error had I known this earlier:

  1. Edit the “append” line of the pxelinux.cfg/default file to include DEBCONF_DEBUG=5
  2. Press Alt-F4 at the point where the automated install hangs to find out what parameter was missing to cause the user prompt.