On multiple threads there is a link to the app store page for High Sierra (which is required for using the combo update link that is at https://support.apple.com/kb/DL1970?viewlocale=en_AU&locale=en_AU)
https://apps.apple.com/us/app/macos-high-sierra/id1246284741?mt=12
Instead of a link for HS - I get a message about Mojave instead. Where is a link to upgrade to High Sierra?
Mac Pro, OS X 10.11
The first link is for the Combo update which requires some version of 10.13 first, only 10.13.6 is available, but you already have it evidenced by to Open button, check Applications...you have an 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.
Or... trash the Install MacsOS High Sierra.app in Applications then a new copy can be downloaded.
..and just for the record - the combo file for 10.13.6 available through apple support gets this message:
...and then it quits.
I am on a Mac Pro mid-2012 running El Capitan. I tried installing a metal-capable GPU and it says I need to be running at least 10.13 in the docs (tried it and sure enough - they are right). I need to upgrade to High Sierra so I can upgrade the video card so I can upgrade to Mojave>Catalina. ARRRRGGGG!!!
What OS are you on now?
The download link for High Sierra 10.13 is not working
