Chosen Solution
We have an independent repair shop, where we heavily rely on having bootable USB installers. Starting at the end of last week none of our drives across devices are able to install software. El Capitan, High Sierra, Catalina on iMacs, Macbook air/pro ect. These installers have worked for years and failed at the same time. “This copy of the install macOS High Sierra application is damaged, and can’t be used to install macOS” We have checked and double-checked the date in terminal, so this is not the issue Anybody have any similar experiences right now?
You fell into Apples failure in their certificate signing! Here’s a bit more: If you’ve got an old macOS install image, it will probably stop working today. Basically, the signing was shorter than what the market was expecting as we are holding on to our systems longer! Here’s a set of links to the updated installers. Jump down to Step 4 in all four: How to upgrade to macOS SierraHow to upgrade to macOS High SierraHow to upgrade to macOS Mojave You can also cheat with your current installers! All you need to do is alter the systems Date to one that was within the window of when the OS was originally released manually. Don’t forget to reset the time server setting back to auto afterwards. Any of the older installers you’ll need to do it that way.
As an example: OS-X Lion (10.7.x) was released July 20, 2011, and was replaced by OS-X Mountain Lion (10.8.x) July 25, 2012. So I reset the systems date to January 2012 to be within the releases’s window. The installer is none the wiser! As the certificates date is within the systems date.
