[Solved] MacOS An error occurred while preparing the installation

If you're here is because you've encountered the error “An error occurred while preparing the installation. Try running this application again."

Today, while trying to reinstall OS X on an old Mac, I came across this issue.

Luckily the solution was much easier than I anticipated, I must warn you though, that this solution will only work in the specific scenario that we’ll discuss now.

One of the reasons this issue occurs is due to an incorrect date on your system. If the date is very different than what the Apple servers expect, it will deny your request for installation.

So, first, lets check if this is the issue that you’re having:

• 1.- From the Mac OS X Utilities menu (at the top of the screen), select “Utilities” and then “Terminal"
  
• 2.- In the Terminal window, type “date” and press return(enter) and check if the date displayed there is correct.
• 3.- If the date and time is correct, then look for a different solution as this article only covers this specific scenario. However, if the date is incorrect, continue reading.
• 4.- to fix the date, we must type the date in the following format mmddHHMMyyyy where
  mm: month
  dd: day
  HH: hour
  MM: minute
  yyyy: year
  
  For example: Today is Wednesday 12th of September 2018 and it’s 12:58 pm. You should write interminal “date 091212592018”
  January 1st 2018 at 3:45pm would be “date 010115452018” and so on.

After doing this, you should be able to perform your installation without any issues!

Please let me know in the comments if this helped you when your issue was related to the system’s date.

[Solved] Boot Camp: Windows cannot locate the disk and partition specified

If you're here is because you've encountered the error "Windows cannot locate the disk and partition specified in the unattended answer file's <ImageInstall> setting.

I had this problem myself recently while trying to install Windows 10 on my 2017, 27‑inch iMac with Retina 5K display which is configured with a 512 SSD drive.

This was the 2nd problem I encountered while using Boot Camp. The first one was "Boot Camp: Your disk could not be partitioned" which I described the solution to in the link.

The issue here was quite simple but it took some time.

Lets address this from the least invasive steps first.

1. Disconnect all external drives. (USB thumb drives, External Hard Drives, SD Cards. etc.) and try again. If your ISO image is on an external drive, copy it to your internal HDD.
   
   If this doesn't work, do not reconnect them back yet.
   
   
2. Get back to MacOS. While your Mac is restarting, hold the "Option" key and select the Hard drive where MacOS is installed.
   
   
3. Undo what Boot Camp has done.
   
   To do this, you will need to open Boot Camp assistant again and "Restore to a Single Volume"
   
   
   
   
   
   
4. Restart your Mac and start the process again, make sure you maintain the changes on Step 1.

And that should be it. That's what it took for me to resolve this issue. Let me know in the comments if this worked for you, if you found a different solution, let me know, so I can add it to the article.

Thank you for reading!