- Insert a USB key with OS X install into Mac (or install disc)
- Power up and hold the Option key down as soon as you hear the startup chime.
- Choose OS X to install
- Once booted into recovery, choose Utilities from the menu and then Terminal.
- Type date into Terminal and hit enter; this displays the date; if it is not the current date, you need to go to the next step.
- Type date into Terminal followed by today’s date in this format [month][day][hour][minute][year] so today is July 11, 2016, 2:15 that would be date 0711141516 then press enter. Of course, your date and time will vary.
- Rerun the first command in Terminal date and press enter; the date should now be fixed.
At this point, you should now be able to continue your reinstall of OS X on your Mac, and the installation error should no longer appear. For whatever reason, the system date matters when installing the OS on your Mac. So if you get that error, don’t panic and think your Mac is toast, try this fix first, and you should be golden.
https://techaeris.com/2016/07/11/change-system-date-os-x-terminal/#google_vignette
Date and time parameter using the format [MM][DD][HH][MM][YY].
Example: April 15, 2022, 11:00 am would be 0415110022, so now would be...
0106161424
Note: The time uses a 24-hour format