Problems installing Mojave from app store

You could try making a bootable copy of macOS Mojave and boot from it.

https://support.apple.com/en-us/HT201372

try again, when booted from the USB click install/reinstall macOS. If the same thing happens, go to utilities>terminal and set the date to Sep 24 2018 by typing:

date  [mm][dd]HH]MM[yy] 

where mm is month and MM is minute.

Peterh1967a wrote:

I don't want to download Catalina just yet, and so I want to download Mojave instead (I am currently running High Sierra). I follow the link to the app store from the apple support site and have downloaded the latest version of Mojave.

When I try to install it (from the app store, not utilities) I get the message "This copy of the Install macOS Mojave.app application is damaged, and can‘t be used to install macOS."

Anyone have a solution please?

You do not say what exact Mac /model /year /size /retina /touchbar is this

or

what exact macOS you are currently running?

Typically a slow internet download speed is what corrupts a download.

Delete the corrupt /damaged .app that you downloaded and empty the trash.

Try again from a different Network, or try using Ethernet connection if your WiFi is suspect.

macOS 10.14 Mojave - Technical Specifications:

https://support.apple.com/kb/SP777

Upgrade to macOS Mojave - Official Apple Support download:

https://itunes.apple.com/us/app/macos-mojave/id1398502828?mt=12