New MacBook Air - update installation failed I have a new MacBook Air. I just bought it and first started it. I try to update it to the latest version, but I get Installation failed. I try to install macOS 10.14.5. 

Where are the updates stored after they are downloaded? Maybe it works if I delete it and download the update again?

I am totally new to macOS any help is appreciated.
I had to disable System Integrity Protection (SIP). Just follow this answer:

https://apple.stackexchange.com/a/361046/333653

Then I had to open a terminal and delete all folders in /Library/Updates with sudo rm -Rf e.g. sudo rm -Rf 041-57076. These are the update files, I need to delete them because they are corrupted because of poor internet connection.

Now I triggered the update again, it began to download the update again and now it works :)

If it does still fail, then try this procedure again, but connect via cable not via Wifi.