Some background: A while ago I found (literally found between garbage on the street) an older (2011) iMac which I intended to be used by my 7 year old son. I never used a Mac myself. The machine started up in High Sierra, with two users accounts (one of which was admin) and a guest account installed. I didn't have any passwords, so I could not do much with it other than try the guest account and see if it worked. All seemed well. At that point I Googled some ways to reset the user accounts to my own. Various sources recommended the same procedure:

  1. Start up in recovery mode with command+R
  2. Use Disk Utility to "Erase" the volume "Macintosh HD" (and in the process format is as APFS, the only option apart from some variants like encryption and case-sensitivity).
  3. Use Install MacOS to install High Sierra on "Macintosh HD" The last step installs fails with a message saying "The recovery server cannot be reached".

At that point I started looking for ways to fix this problem. The most obvious is of course to check the internet connection, which I verified with Network Utility (ping, dns lookup, trace route all work fine). Then I read somewhere that the installer verifies the date. I used Terminal to resync the system clock (which was off only by 0.4s), to no avail.

I also tried Internet Recovery (command+option+R) which downloads an installer for MacOS Lion. This also fails with the same message about the recovery server not reachable, after making sure internet is connected.

Then finally I asked a friend to prepare a bootable USB stick with a High Sierra installer. Again this fails at the same step, also with internet connected.

In the log file there's a line saying "Failed to load catalog https://swscan.apple.com/content/catalogs/...". That's probably what the error message is about. screenshot Installer Log

The log file also mentions that the file system is not suitable, but that's only after I tried Lion, in which the Macintosh HD volume was formatted to MacOS Extended (Journaled) file system (which seems to be the same as HFS?, a bit confusing), as shown in Disk Utility: screenshot Disk Utility

The file system issue is another problem than the problem of not reaching the recovery system, I believe, but I could be wrong.

  • 1
    This is a bit confusing. If you're running from Internet Recovery, yes, High Sierra might struggle to see the App Store, but from USB there is no internet connection required. btw, you cannot install HS onto APFS, it must start with HFS & it will do the conversion itself [yes, that's irritating]. See apple.stackexchange.com/q/315880/85275 and apple.stackexchange.com/q/309399/85275
    – Tetsujin
    Jun 20 at 8:10
  • This iMac had High Sierra installed before, so there is a Base System present. Disk Utility lets me only format Macintosh HD as APFS (and encrypted/case variants), not HFS. And yes, the USB install does prompt for a Network, it is required. Probably what is on the USB drive is the same as is already in de Base System partition, not a full ISO. The size of the USB installer is 1.39G.
    – marc
    Jun 20 at 11:14
  • 1
    It’s tough to follow your trials and tribulations in comments. Would you be so kind as to edit with some clarifications, screenshots or Terminal output (preferable)? A lot here doesn’t make sense. Also, start by erasing your drive with the Terminal command diskutil partitionDisk /dev/diskX 1 GPT JHFS+ “New Name” 100%. The install High Sierra. You should have no “base system/format” when you erase a drive.
    – Allan
    Jun 20 at 14:39
  • 1
    Your [now removed] solution still draws some wrong conclusions, as do your comments. 1. Mac OS Extended (Journaled) is HFS+. 2. Apple has never issued the OS as .iso, only ever as .dmg so if you're starting from an iso, you have a non-Apple file. 3. Just because High SIerra is no longer supported doesn't mean you can no longer get it directly from Apple [this was linked from my first comment]. 4. USB installs do not need to access the internet at all, so you're still doing something wrong there.
    – Tetsujin
    Jun 21 at 10:11
  • 1
    I should also point out that much of the information regarding installing OS X/macOS, that is posted on the internet, is wrong. Some was always wrong, while other information is now wrong (i.e. outdated) do to changes made by Apple. Many of my own older posts are now wrong do the changes made by Apple. I image in the future much of what is posted here will be wrong. The best information comes directly from Apple. They do make a effort to keep their websites up to date. Jun 23 at 17:53

2 Answers 2


If you can not install High Sierra by using the High Sierra installer application stored in the High Sierra Recovery partition or from booting to Internet Recovery, then the steps below could be used as an alternative.

The procedure installs OS X Mountain Lion, then uses OS X Mountain Lion to do a clean install of macOS High Sierra.

  1. Create a bootable USB Mountain Lion installer. The instructions are given in the section titled “How to Create a USB Flash Drive Mountain Lion Installer from OS X/macOS Recovery” of this answer.
  2. Follow this answer starting at step 2. Note: At step 6, substitute http://maclinks.publicvm.com for the link How to download macOS.

Another alternative is to find a bootable High Sierra installer on DVD from someone, which can be inserted in the iMac, and selected for booting after starting up with Option (Alt) pressed.


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