Can’t choose startup disk after wiping hard drive from OSX Utilities I’m helping someone with their old laptop (17”, mid-2009, if that matters). I restarted with cmdR to load OSX Utilities, and I used Disk Utility to wipe Macintosh HD, overwriting it three times and formatted as OS X Extended (Journaled). 

Afterwards, after successfully connecting to my Wi-Fi, I clicked on Reinstall OS X, and it’s giving me the option to set up El Capitan (the OS X that’s installed, and from what I can tell, the latest that can be installed). But when I hit continue, it gives me an error message:


  An error occurred while preparing the installation. Try running this application again. 


I get the same message every time I try. So I thought I’d try quitting OS X Utilities without reinstalling OS X and see what happens. 

After clicking on Choose Startup Disk, I get a blank list to choose from, with a restart button. No startup disks are available. Clicking restart, as one might expect, yields the following error message:


  You can’t change the startup disk to the selected disk.
  
  Startup Disk could not gather enough information on the selected disk. 


So I quit Startup Disk and went back to Disk Utility, and I tried running First Aid on both Macintosh HD and OS X Base System. Neither one had any issues. 

So what is my issue? Did I mess up when wiping the hard drive? Do I just need to reformat it? Is there anything I can do, or have I rendered this computer a hunk of junk? Also, how do I prevent this in the future?
Well, your having wiped and reformatted the HD, there IS no bootable volume on that machine, so that HD cannot be selected as a bootable startup disk, as it has NO data on it at all, let alone a full Mac OS with which to boot.

You'll need to see about getting that OS installer downloaded set up as an ISO on optical media using a different machine to do this, and then running the installer on the target machine from the optical media I think, given the issues you're seeing when trying the network install option.