<< Solved >> 10.15.5 Supplemental Update: macOS could not be installed on your computer

[biskero]

I saw that on USB stick the Catalina installer is from May 27th while combo is from May 28th, do I just convert the combo dmg to app and create a new USB installer ?

 

[Gobias]

I got this issue on my Catalina installation, now I downloaded the combo .dmg, I have a stupid question, how do I create the usb installer like I have done for Catalina?
What is the process?

thx

ok, I am confused. I tried to install Catalina, got to the "macOS could not be installed on your computer". The fix is to use the 10.15.5 combo update, I downloaded, is a .dmg, what do I do now?

@Gobias how do I install the combo update?
thx

I got that error when updating from 10.15.5 to the 10.15.5 supplemental update. I had to restore from a clone of my startup disk that had 10.15.4, and then I installed the 10.15.5 combo update.

You must have an older version of Catalina (10.15.0–10.15.4) already installed to use the combo update. As Feartech said, you can't use the combo update to make a USB installer. You have to download the Catalina package from the app store to make a USB installer.

 

[biskero]

I cannot do this process since I do not have a system working. The Catalina installer from the app store did not install and got this error. So you are saying that this is just an update once you install Catalina! If so I am stuck !

so I could try 10.15.0 instead of the latest?

I got to this page, which one should I try? also how do I create a usb stick from a dmg file?

thx

 

[UtterDisbelief]

I cannot do this process since I do not have a system working. The Catalina installer from the app store did not install and got this error. So you are saying that this is just an update once you install Catalina! If so I am stuck !

so I could try 10.15.0 instead of the latest?

I got to this page, which one should I try? also how do I create a usb stick from a dmg file?

thx

Hi there.

You have a UniBeast installer drive, yes?

If not, and you can't boot this system, then you are going to need to create another UniBeast installer and re-install Catalina. If you do this without formatting it should preserve all apps and data already on the destination drive.

 

[biskero]

I have UniBeast but where do I get a Catalina 10.15.4 .app from, searching Apple sites but are all dmg

 

[UtterDisbelief]

I have UniBeast but where do I get a Catalina 10.5.4 .app from, searching Apple sites but are all dmg

If you have a UniBeast installer already to hand, use that to re-install as I suggested. What version of macOS does it use?

The App Store will only offer the latest version of macOS, which at least works around the update problem as your new installer will then be the current one.

 

[biskero]

ok wait.
The UniBeast uses the Catalina 10.15.5 installer that in my Application folder.
This Catalina 10.15.5 from the store does not install, I get the error message that I posted.
So they suggested me to go back a version, which from what I understand is 10.15.0 since all the others are updates.
I cannot install the combo or updates, I mean I cannot create a new usb installer since I need a full OS not an update.

Is this correct or I going nuts?

Is there a way I can download the original Catalina 10.15.0 and try that?

 

[biskero]

btw when everything is installed, I can just install the combo update without doing anything else?

 

[Gobias]

So they suggested me to go back a version, which from what I understand is 10.15.0 since all the others are updates.
I cannot install the combo or updates, I mean I cannot create a new usb installer since I need a full OS not an update.

Is this correct or I going nuts?

Is there a way I can download the original Catalina 10.15.0 and try that?

To clarify, I wasn't suggesting that you install an earlier version of Catalina. When I couldn't get the update to work, I just restored from a working backup that happened to have an earlier version on it.

Apple only lets you download the latest version of Catalina from the app store, so that's all you can use to create a USB installer.

If you are getting an error with your 10.15.5 installer, you can try re-installing Catalina without reformatting your drive as UtterDisbelief suggested.

If re-installing doesn't work, and you can't find any other solutions, you could also try reformatting your drive, performing a clean installation of Catalina, and restoring your files from a backup afterward.

 

[biskero]

yeah I got it, it's a pain in the ass! Tried already your suggestions, no go!
Anyway I found a Catalina 10.15.0 from October 12, 2019, seems ok.
Doing the process right now, will report results.

Anyway, the combo can be installed after I have done the Catalina installation and modify the EFI?
Like a normal update?