I tried to down load Mojave and got the following message,This copy of the Install macOS Mojave.app application is damaged, and can‘t be used to install macOS. what can i do??

Choose Applications from the Finder's Go menu, throw the existing installer away, and try downloading it again; you may need to go through an intermediate version or use a computer running a newer OS.

(211484)

I too had this problem and downloaded Mojave several times with the same result.

It seems the file is not literally damaged. Rather it is indicating a problem somewhere.

Once I deleted the old Installer file for High Sierra (Finder, Go, Applications. Drag file to Trash and empty trash. Reboot) it all worked fine. The Mojave installer was bouncing in the dock and a click did the rest.

If you get a corrupted message...

Naw, not damaged, it's just that you have an old copy already in Applications, there are 2 cures...

Disconnect from the Internet & set the Date back to 2014, then you can run the Install MacsOS Mohave App in Applications, so expired Certificates are not expired.

Or... trash the Install MacsOS Mojave.app in Applications, empty trash & restart, then a new copy of a more recent version can be downloaded..