How to Download Mountain Lion on 2011 MacBook Pro so I can upgrade to High Sierra

In that case, try the following. I assume the subject Mac is running OS X version 10.7.5 and its Safari version is 6.1.6. Although I no longer have any Macs fitting that description and cannot be completely certain it will work, the following technique ought to work, although there could be some roadblocks that may require additional effort to overcome.

In what may be a historical first, the YouTube video is actually correct. You need to upgrade that Mac to El Capitan first, followed by upgrading to High Sierra, which is the latest version it will be able to run. Unfortunately Apple recently made upgrading certain older Macs difficult for reasons nobody seems to be interested in addressing.

First, upgrade from Lion to El Capitan. An intermediate stop at Mountain Lion is not required. You will need to use the following technique for a number of technically mind-numbing reasons we can discuss some other time.

Using the 2011 MacBook Pro, open the Terminal app - it is in your Mac's Utilities folder, and looks like this:

• To open the Utilities folder, select the Finder's Go menu > Utilities.

Select the entire line that follows below (triple-click to select the entire line), select Edit > Copy, and then Paste it into the Terminal window:

curl http://updates-http.cdn-apple.com/2019/cert/061-41424-20191024-218af9ec-cf50-4516-9011-228c78eda3d2/InstallMacOSX.dmg --output ~/Desktop/InstallMacOSX.dmg

... then press the Return key.

Keep that Terminal window open. If some kind of error appears please let me know what it says (you can copy from Terminal and paste it here).

If all goes well a InstallMacOSX.dmg file will appear on that Mac's Desktop. Don't do anything with it yet. Terminal will show the file download progress with labels Time Total / Time Spent / Time Left which you can watch if you have nothing better to do.

Wait for the Terminal app to stop updating those values. It will eventually finish and show the prompt you saw when you opened it. When it does, double-click the InstallMacOSX.dmg file to open it.

Please let me know if that works first. If it does that will bring us to the next step, which will be to install High Sierra from App Store. I'll provide those instructions pending your report of success thus far.

Did that error appear immediately after pasting that Terminal command?

If so I have no explanation. I confirmed it using three separate Macs running three different older operating systems. It worked perfectly on all of them so all I can suggest is to be sure you're following those instructions exactly. I realize that doesn't help you. There is something wrong but I have no idea what it might be.

It's downloading El Cap on an eligible iMac running Snow Leopard — Lion's immediate predecessor:

Last login: Mon Dec 11 18:36:23 on console
john-iMac2:~ john$ curl http://updates-http.cdn-apple.com/2019/cert/061-41424-20191024-218af9ec-cf50-4516-9011-228c78eda3d2/InstallMacOSX.dmg --output ~/Desktop/InstallMacOSX.dmg
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  4 5917M    4  267M    0     0  3855k      0  0:26:11  0:01:11  0:25:00 3840k
  4 5917M    4  271M    0     0  3854k      0  0:26:11  0:01:12  0:24:59 3784k
 45 5917M   45 2714M    0     0  3787k      0  0:26:39  0:12:14  0:14:25 4070k

If you don't get anywhere there is at least one recent anecdotal report of bringing a Mac to an Apple Store who installed High Sierra for the asking.

That's all I can suggest for now.

I am running 10.7.5 and Safari is 6.1.6

That is exactly as it should be, and the condition in which that Mac should be transferred to a new owner. You're finished.

That Mac's version of Safari will be unable to load any website requiring secure connection protocols. It can be upgraded, but that is a task for its new owner. Since you are giving it away, there is nothing else you need to do. If its new owner wants to upgrade its operating system he or she can come here and ask for guidance.

👍

Great! Glad to hear it.