The issue is that the "OSXRESERVED" partition, that is created as part of the bootcamp process, is only 8GB in size. The drivers and ISO files need to save in this partition during the process and the 8GB is no longer enough to accommodate these files. The fix: Download your desired windows ISO. Run the boot camp assistant and download the drivers from the "Action" menu. Run the boot camp assistant again, but quit when you see "copying files" on the progress bar. The partitions should be made by this time and it is now trying to copy the files to OSXRESERVED. Run disk utility, highlight OSXRESERVED and click Partition. Highlight the OSXRESERVED wedge and click "-" to remove it. Now click the "+" and create a new 16GB (or whatever size you need) partition named OSXRESERVED, set it to ExFAT format, and hit OK. The OSXRESERVED partition should mount itself. Copy and paste the contents of the drivers folder into the OSXRESERVED partition (should be 2 folders and a file if memory serves correct). Not open the ISO and copy the files from it into OSXRESERVED as well. In disk utility, right click the greyed out "bootcap" drive in the "internal" list and "Mount" it. Restart your computer and hold "option/alt" during startup to bring up the boot disk menu. Select the "Windows" disk and hit enter. You should now be at the windows install menu. Go through until you get to the disk select menu. Select the "bootcamp" partition, hit format, and then next. From here you should be able to follow the prompts until the computer reboots to windows.