Cannot update Catalina 15.2

[m.g.mcc]

I have a 13" MacBook Air 2018 running Catalina 15.2 but trying to update it fails with this message:

macOS could not be installed on your computer

An error occurred installing macOS. To use Apple Diagnostics to check your Mac hardware, shut down, press the power button and immediately hold the ‘D’ key until the diagnostics begins.

Quit the installer to restart your computer and try again.
​

When I run diagnostics, no problem is found. If I try to reinstall the operating system, I get the same error. The only thing I can do to get the MacBook working again is to restore a Time Machine backup. Any suggestions to move forward from this impasse?

 

[ferrarr]

Have you tried safe mode?

How to use safe mode on your Mac - Apple Support

 

[m.g.mcc]

Brilliant, thank you. Starting the MacBook in Safe Mode and then running the update has got it updated to 15.4. I had tried so many times, first trying to update to 15.3 and then to 15.4, with the consistent fail message.

Thanks for your help and I will know what to try if the same happens in future.

 

[IWT]

Wonderful that you got it sorted and a big thank you to Bob.

Another option might have been to download macOS Catalina 10.15.4 Combo Update from here: Apple - Support - Downloads

Always useful when updating by more than one point (ie from 10.15.2 to 10.15.4)

Ian

 

[chscag]

Brilliant, thank you. Starting the MacBook in Safe Mode and then running the update has got it updated to 15.4. I had tried so many times, first trying to update to 15.3 and then to 15.4, with the consistent fail message.

Thanks for your help and I will know what to try if the same happens in future.

The fact that you were able to install the update while running in Safe Mode tells us that something you have installed was interfering with the update process. Safe Mode removes all third party startups and kexts from starting up when you boot.

Take a look at what you have installed and running. Any anti-virus software? Any clean up software? etc.

 

[m.g.mcc]

The fact that you were able to install the update while running in Safe Mode tells us that something you have installed was interfering with the update process. Safe Mode removes all third party startups and kexts from starting up when you boot.

Take a look at what you have installed and running. Any anti-virus software? Any clean up software? etc.

OK, thanks, I will try to check that out. I have two Mac Minis and a MacBook Pro and am not aware of having anything installed in the MacBook Air that isn't also installed in the other Macs. No anti-virus software installed, only Malwarebytes and CCleaner neither of which run in the background and both are installed in the other Macs.