Need help updating MacBook Air 2020 from 10.15.5 to 10.15.7

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MacBook Air 2020
i5, 8 GB RAM, internal SSD is 256 GB formatted as APFS

I was good with Macs up through 2010 or so, but haven’t done much since. A friend has this MB Air with specs above, I wanted to upgrade it to the latest 10.15.7. The Wikipedia article on Catalina has a list of the updates required to bring the Mac up to 10.15.7 (I know that Combo updaters are needed):

  1. macOS 10.15.7 Combo Update
  2. macOS 10.15.7 Supplemental Update (Combo)
  3. Security Update 2020-001 (Catalina)
  4. Security Update 2021-001 (Catalina)
  5. macOS Catalina 10.15.7 Supplemental Update 2
  6. Security Update 2021-002 (Catalina)
  7. Security Update 2021-003 (Catalina)

This Wikipedia article has download links at apple.com where each of the 7 updaters can be downloaded.

I have an external USB enclosure with SSD formatted as HFS+ Journaled. On a PC and using a download manager, I downloaded all 7 updaters to my local disk, then copied them to the external SSD. (I could not find checksums for the 7 installer DMG files, so I’m not sure they are not corrupt.) I attached the external SSD to the MB Air, it was recognized, I double-clicked the DMG file for update #1 (macOS 10.15.7 Combo Update) then launched the installer (PKG). Got an error saying the update had failed, tried again once or twice, them copied DMG to internal SSD and launched the installer from there, same error. Rebooted into Safe Mode, tried installing, same error.

I then tried to reboot and BINGO the installer was running, the screen was black with white Apple logo and progress bar. After a reboot or 2, the Mac was updated to 10.15.7. I then tried update #2, macOS 10.15.7 Supplemental Update (Combo) - got an error with dialog box showing the internal SSD (Macintosh HD) with text saying the update was not suitable (I forget the exact word) for that volume. At this point we ran out of time and I stopped trying to install the 7 updates in sequence.

In a future session, I really need to get the remaining updates installed - update #2 contains the fix “Resolves an issue where macOS would not automatically connect to Wi-Fi networks” which seems highly desirable… so my questions are:

  1. Are all 7 updates needed for this Mac? (The notes for Supplemental Update 2 mention only two older MacBook Pro models)

  2. How do I get the remaining updates installed?? I have read about System Integrity Protection and the “csrutil disable” command - is that what was keeping Update #2 from installing?

Note - in a previous session we had noticed that, in the control panel, the Big Sur update was being offered. I recommended she hold off and we disabled it, but at the end of this last session, Security Update 2021-003 was being offered, but we did not install it. Are the security updates cumulative?

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Should I ask why you don’t want to just go to the Software Update panel in System Preferences?

You don’t have to upgrade to Big Sur to get the other updates. Underneath the box containing the request to upgrade to Big Sur, if there are other updates available (e.g. Catalina updates), you will see text saying “Other updates are available” and a link named “More info…”. Click on “More info…” to view, select and install these other updates.

I can’t upload a screen shot from my computer because I don’t currently have any pending Catalina updates, but I did find a blog post that has several: Podfeed Podcasts: How to Update macOS Catalina and Not Upgrade to Big Sur.

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To echo David, you should be able to install these updates from Software Update in the System Preferences. Normally, you wouldn’t have to separately install every single update. In infrequent circumstances, some updates may not be available until after a preceding one, but Software Update has gotten pretty good at figuring out and installing all the OS and security update components you need in one go. Extra updates tend to be things like Safari updates, which don’t require a reboot.

You DO NOT need to disable System Integrity Protection to install updates from Software Update or the Mac App Store. If you have a specific app that requires SIP to be disabled in order to run, that app will tell you that (and you should do that only if you really trust the developer). There aren’t many major ones that do anymore, as most things that would have run into issues with that have been rewritten to use permissions you grant from the Security & Privacy pane in System Preferences. If you don’t know whether you need to disable SIP for something, you probably don’t.

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Sorry for delay, thanks for the replies. My friend is a server in a restaurant I frequent, that is the only time I see her. She brought her MBA again, we installed Security Update 2021-003 from the Software Update control panel, it installed OK, and there was a message that there were no more Catalina updates. Sometimes I make things more difficult than they need to be…