Sorry for a lengthy post. This is an uncommon situation for most people so please read only if the topic particularly interests you.
I bought a used MacBook Air 7,2 (MBA1) last summer, which came with no SSD. I thought it was no biggie because it was my plan to install an M.2 NVMe SSD anyway and everything seemed to be working fine.
I own another MBA7,2, (MBA2) which I bought new in 2015 and was comparing the two for some troubleshooting last week. Both had NVMe M.2 SSD (XPG SX8200 Pro) with short Sintec adapters running Mojave 10.14.6 (18G7016), but I realized MBA1 had an El Capitan or Yosemite Boot ROM (171) while MBA2 had the latest (425).
I did some reading on this forum and figured out firmware updates were done only during macOS update/upgrade process since several years ago. Many people also noted that an OEM SSD (or whatever is on Apple's approved hardware list for this purpose) was required to be installed for a Boot ROM update while others reported success with a third party SSD (including SX8200 Pro) installed. Hoping the latter was my case, I spent several hours with frustration and no success. The "bless" command method didn't work either.
I ended up obtaining a used OEM SSD and was ready to update it to 425, however, my stupid curiousity drove me to find out when Apple actually lifted the "original SSD" requirement for Boot ROM upgrades, if they actually ever did. I started from El Capitan then performed every possible update/upgrade up to Big Sur while swapping the OEM SSD and the SX8200 Pro each time.
Now the mystery is solved. MBA1 must've had its original SSD removed before El Capitan 15G22010, which got it stuck with 171. MBA2 didn't get a third-party SSD until last summer when its Boot ROM had already been at least 188 and was able to get it updated during subsequent macOS updates/upgrades. Also note that how the formatting changed somewhere between 178 and 188, which seemingly coincides with the end of the "original SSD" restriction.
In conclusion, my advice is that if you find yourself in this rather uncommon situation where your Boot ROM isn't up to date and you don't have an OEM SSD, obtaining one seems to be the most practical path to overcome the restriction. It just needs to be installed, and properly recognized by the system to pass the check. Then any of the following on ANY volume on the mac should accomplish the Boot ROM update.
Useful links:
eclecticlight.co
eclecticlight.co
eclecticlight.co
eclecticlight.co
eclecticlight.co
I bought a used MacBook Air 7,2 (MBA1) last summer, which came with no SSD. I thought it was no biggie because it was my plan to install an M.2 NVMe SSD anyway and everything seemed to be working fine.
I own another MBA7,2, (MBA2) which I bought new in 2015 and was comparing the two for some troubleshooting last week. Both had NVMe M.2 SSD (XPG SX8200 Pro) with short Sintec adapters running Mojave 10.14.6 (18G7016), but I realized MBA1 had an El Capitan or Yosemite Boot ROM (171) while MBA2 had the latest (425).
I did some reading on this forum and figured out firmware updates were done only during macOS update/upgrade process since several years ago. Many people also noted that an OEM SSD (or whatever is on Apple's approved hardware list for this purpose) was required to be installed for a Boot ROM update while others reported success with a third party SSD (including SX8200 Pro) installed. Hoping the latter was my case, I spent several hours with frustration and no success. The "bless" command method didn't work either.
I ended up obtaining a used OEM SSD and was ready to update it to 425, however, my stupid curiousity drove me to find out when Apple actually lifted the "original SSD" requirement for Boot ROM upgrades, if they actually ever did. I started from El Capitan then performed every possible update/upgrade up to Big Sur while swapping the OEM SSD and the SX8200 Pro each time.
| After installing... | Boot ROM version was updated to | Was OEM SSD required for update? |
| El Capitan 10.11.6 (15G31) El Capitan 10.11.6 (15G22010) Sierra 10.12.6 (16G29) Sierra 10.12.6 (16G2136) High Sierra 10.13.6 (17G66) High Sierra 10.13.6 (17G14033) High Sierra 10.13.6 (17G14042) Mojave 10.14.6 (18G103) Mojave 10.14.6 (18G7016) Catalina 10.15.7 (19H15) Catalina 10.15.7 (19H114) Big Sur 11.1 (20C69) | MBA71.0178.B00 188.0.0.0.0 195.0.0.0.0 425.0.0.0.0 | Y Y N N |
Now the mystery is solved. MBA1 must've had its original SSD removed before El Capitan 15G22010, which got it stuck with 171. MBA2 didn't get a third-party SSD until last summer when its Boot ROM had already been at least 188 and was able to get it updated during subsequent macOS updates/upgrades. Also note that how the formatting changed somewhere between 178 and 188, which seemingly coincides with the end of the "original SSD" restriction.
In conclusion, my advice is that if you find yourself in this rather uncommon situation where your Boot ROM isn't up to date and you don't have an OEM SSD, obtaining one seems to be the most practical path to overcome the restriction. It just needs to be installed, and properly recognized by the system to pass the check. Then any of the following on ANY volume on the mac should accomplish the Boot ROM update.
The "bless" command method
Updating the OS
Upgrading the OS
Installing the OS
Useful links:
Which EFI firmware should your Mac be using?
A checklist of the latest EFI firmware versions which should be running on each recent Mac model.
eclecticlight.co
Which EFI firmware should your Mac be using? (version 2)
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eclecticlight.co
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eclecticlight.co
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