Solved > Installing High Sierra - Error: Installer Damaged - DO NOT DOWNLOAD again, here is the Trick!

Dec 30, 2018
Intel i7 4770K Quadcore 4x3,5Ghz 8MB L3 Turbo
GeForce GTX 980
MacBook Pro, Mac mini
Hey Folks, i getting here so much help, so i will give something back :)

1. Installer is Damage and can not be used (Apple Error, should work for Mojave too)
If you have the problem, while installing High Sierra, that the installer tell you "it is damaged, please load again.."
- you will came up to the point, that you can not download it again from apple, and at all: you do not need!
And Apple just take away the links to download it fresh, and other downloads will have the same problem.
Do not delete yor installer, it is fine!!! You can use it! Its nothing special or new you need to do :D

At first: Create your bootable USB installer Stick, try to run to get the firmware update first, if you did not already :)
Than All you need to do is:
A. Make sure internet connection is offline
B. Restart and Boot from your installer Stick, run terminal and change the date.
C. Type in terminal: date
(to see current system date)
D. Change date with: date -u (month)(day)(Hour)(Minute)(Year)
Example that worked here: date -u 1218180818
E. Exit Terminal - Now you can install dirctly from your boot Stick ;)

May be, it work without rebooting to usb stick, i did not try. May be next time, or somebody can give feedback to this?
The error is caused by a certificate, that was generated at the date from the download - and this date expired

Another Tip:
Do not try the --converttoAPFS command with a spinning drive, thats only for SSD.
Or you will get: Helper Tool Crashed...

Have good time and stay healthy!