When I try to install mac os high sierra using internet recovery, i get a frozen black screen with an exclamation mark and a error message saying "apple.com/support -3403F". I have tried recovering from multiple locations using different wifi's as well as completely open firewall settings on my home router. My question is, what is causing this, how do i debug it, and how do I fix it?


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That indicates your machine can’t reach the internet.

Troubleshooting this will be challenging unless you have network / wire shark capabilities and can make sure the packets from this machine are going unhindered to Apple’s servers.

In practice, this is far easier to diagnose by using a second Mac on this network to see if it can boot to recovery. If not - you know it’s the network. If the second can boot - you have a hardware failure or network card failure on the problem Mac.

Taking the suspect Mac to another network that is known to be good (or just taking it to 4 or 5 networks and assuming one of them has to be OK) can also help you isolate if the problem is the network or the hardware.

Lastly, setting up a caching server on your local network would let you see those logs and be sure the Mac in question was requesting the correct recovery image from the internet.

Content caching is a super power move, since you only download one copy of each asset, then your local network accelerates all further installs and boots.

  • @DanRan I would probably want to run the latest Mojave’s installer to ensure all firmware is upgraded. Then erase and go back to an older OS if you want. The new macs with T2 chips will be far more resilient to exploits, but that involves cost. I’ve gotten that error when we were rate limited and when the Apple servers were overloaded. We had a lab with 50 iMacs that got our IP rate limited one day when all of them booted to internet recovery without a local caching server. Sounds like you are pretty sure it’s not a temporary issue, though. – bmike Jan 5 at 21:40

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