High Sierra Upgrade

You have downloaded an update installer, not an upgrade installer. How to upgrade to macOS High Sierra.

Before You Upgrade macOS

1. Fix any problems before upgrading.
2. Run First Aid in Disk Utility while booted from your Recovery HD.
3. Backup. Make a bootable clone using CarbonCopy Cloner or use TimeMachine.
4. Be sure your startup disk has 18-20GB of free space during the installation.
5. Upgrade third-party software for compatibility. See App Compatibility Table - RoaringApps. If you have mission critical software, then DO NOT upgrade until you know that software is compatible with the version of macOS you are about to install.
6. Disconnect all third-party peripherals.
7. Download the installer which will be in the Applications folder. Quit the installer after it opens, then make a copy of the installer and save it in the Downloads folder. The one in the Applications folder will be deleted after a successful installation.
8. The download is large, anywhere between 5 and 9GBs. It takes time to complete. Be patient.
9. Double-click on the installer in the Applications folder. Click on the start button to begin the installation.

It sure sounds like you were trying the 10.13.6 Combo update.

Try this browser & link...

https://brave.com/

https://itunes.apple.com/app/macos-high-sierra/id1246284741?mt=12

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 High Sierra App in Applications, so expired Certificates are not expired.

Or... trash the Install MacsOS High Sierra.app in Applications then a new copy can be downloaded.

Replying to my own message. It turns out that I was using Firefox. The trick was to use Safari.

How much free space is on the drive?

Have you used Disk Utility to check the drive?

Have you tried it in Safe Mode?

Safe Boot from the HD, (holding Shift key down at startup), does the problem occur in Safe Mode?

I figured out what the issue was! I was downloading it on Chrome instead of Safari. I now have High Sierra and everything worked! Thanks!

Are you looking for 10.3 Panther, or 10.13.0 which is not available because Apple only lets you download the latest 10.13.6?

Unfortunately, the App store tells us that the upgrade is unusable. Is it no longer viable? The actual message is, "This copy of the Install macOS High Sierra application is damaged, and cant be used to install MacOS."

Advice?

Initially, I was having an issue with the High Sierra installer. I was able to remove the old installer from the Applications folder and download a new one. When I went to install, it said "an error occurred while preparing the installation. Try running the application again." Any thoughts?

I found this thread because I'm having the same problem.

I had found the link you gave above. It isn't working for me. Any tips?

I'm on 10.12.6 Sierra (on a 2010 iMac). When I clicked on your link it said it needed to open it in an application and suggested itunes. When I did that it said "Item Not Available" (and indicated it was not in the US Store. I tried it again, but chose the "App Store" instead of itunes. Nothing happened. Am I missing some sort of update or is High Sierra no longer available???

Thanks!

UGH, c'mon, not a geek

What do you need help with & did you originate this thread using a different login?

By the way, usually there is a box for one to accept the software Agreement by clicking on it. None appeared.

Any luck with this?

No I give up. I'm staying with Sierra for now.