When running TechTool 11 Check Computer, a disk titled "InstallESD" appears. What is that? Can I safely delete it? Before running TechTool, I clicked on "Install macOS Mojave" in my Applications folder. I was curious about upgrading from High Sierra. Could the "InstallESD" have come from my doing that? I did not complete an upgrade because further research said it was best to upgrade from the App Store.
MacBook
I'd suggest running a few web searches when you're looking into these, as—in this cases—that InstallESD filename will be all over the place on the 'net. That file one of the pieces central to the old manual-build procedure for creating a bootable installer from a OS X installation kit downloaded from Apple.
Do you have any idea where it came from?
Yes, everybody has it, many never see it, it's a part of every OSX installer for quite awhile, at least since 10.10.x
InstallESD
