can't install High Sierra

[ozhawk4]

I keep getting a message that says that version of High Sierra is damaged (mind you that is the one from the App Store). If the App Store version is damaged, how the heck am I supposed to actually update my software?

 

[CoastalOR]

I keep getting a message that says that version of High Sierra is damaged (mind you that is the one from the App Store). If the App Store version is damaged, how the heck am I supposed to actually update my software?

When did you download High Sierra? The certificate expired 10-24-2019.
You may need to download a new copy. See Step 4 for the App Store HS link:

How to download and install macOS - Apple Support

Download and install current or previous versions of the Mac operating system on compatible Mac computers.

support.apple.com