Mac computer system downgraded to 10.15 Catalina (2020 last generation intel)

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You don’t need to look at this part of your thoughts> <
I bought a mac in July 2020 to find a job. After finding a job, I have been using the company’s mac, and my own mac has been idle. At the end of 2020, the M1 was not only cheaper than the intel I bought, but also better to use. I felt backstabbed == I calculated it at the time and sold it immediately. I haven’t used the almost brand new intel for M1 for half a year.

One time, I updated Intel from 10.15 to 11 BigSur. From the end of 21 to now, I have been using it intermittently for about a year. In my experience, I opened a few browsers before doing anything. Although I know that it is a common problem with Intel, and now the system has been released to 13 Ventura. The M1 I use for work has been updating. Entura, in fact, the experience is still good, but it is said on the Internet that Intel is still the best to stop at Catalina, so I have the idea of ​​​​downgrading to Catalina for a period of time, using it for a while, and then upgrading to Ventura to use it.

Preparation

Mac cannot be directly downgraded. Even if you download the required system version from the official website ( How to download macOS ), you can see the program in the application, but you cannot install it directly, as shown in the figure below

  1. Click Catalina on the official website: How to download macOS , it will open the following page in the App Store, click Get to start downloading the system, it seems that you can’t find it directly in the App Store
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  2. After the download is complete, you can find it in the Finder application, but clicking it will prompt you that it cannot be installed because it cannot be downgraded .
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  3. To downgrade, you need to press and hold the mysterious shortcut key when booting to enter the simplified macOS. Is there a safe mode similar to win? Downgrading requires erasing the boot disk, which is called formatting and clearing, so back up the files that need to be backed up before starting

Downgrade system steps (networked)

Select the shortcut keys to be pressed during the boot phase

According to requirements, press and hold the corresponding shortcut key before the Apple icon appears on startup until the globe icon appears. The official address of the shortcut key is: Mac startup key combination , other macOS installation options

  • Option-Command-R, on an Intel-based Mac, gets the latest version of macOS compatible with the Mac;
  • Shift-Option-Command-R, on an Intel-based Mac, gets you the macOS that came with your Mac, or the closest thing to it that's still available.
    The last-generation intel factory system in my hand is the 10.15 Catalina I need now, so I used Shift-Option-Command-R during the boot phase

Into Simplified macOS

If you fail to enter the earth icon page, then shut down and restart, and hold down the shortcut key before the Apple icon appears and do not let go. After entering the page in the picture below, wait patiently for the progress bar to finish. This is the classic Apple 1min. Don’t believe its countdown = = Occasionally you will encounter some failures to enter. Don’t panic. He gave a URL to go in and see the instructions. Although in fact I didn’t find out how to exit this page from the paragraph
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on the official website. Finally, press and hold the power button to force shutdown and start again .


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Activation Lock Page

After the earth progress bar is finished, there is still a step to activate the lock. If you don’t remember the password, it is recommended to try it elsewhere. I don’t know what will happen if you enter the locked account here = =
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macOS Utilities Page

Because it is downgrading the system, you must first erase the disk, first click "Disk Utility"
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erase disk

If you have already emptied the disk during the previous backup, it is best to come here to erase it with one click. After all, there are some system things besides the files that can be deleted. Select
Macintosh HD - Data, and then click "Erase".
If you are careful, you will find that there is an Update disk here? segment? I did a little research and found that this is something like an automatic backup brought about by the downgrade operation. After a successful downgrade, delete it. For now, you can leave it alone.
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Install downgrade system Catalina

After the disk is erased successfully, close Disk Utility, and you will return to the macOS utility page, and then click to reinstall macOS. The utility also has the option of time machine, so it means that it has been stored with time machine before, and you can also return to the saved state with one click. Because I used Shift-Option-Command-R to enter, so he will install macOS Catalina for me by default. I have been stuck in this kind of place and tried again==
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About reinstalling the system from a USB flash drive

I haven’t studied it yet hhh
is roughly the same as win, use a USB flash drive to make a boot disk, and enter the simplified version of macOS similar to the above

Related reference blog

https://www.zhangshilong.cn/work/328891.html (This person’s blog still has a lot of strange operations on the system that you can look through, but the search function can’t be used, which is a bit troublesome) https://blog.csdn.net/weixin_47879434/article/details/124486240 https://blog.csdn.net/zz00008888/article/d etails
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123787299
https://blog.csdn.net/qq_44636114/article/details/126444237

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Origin blog.csdn.net/XunCiy/article/details/128166202