Recover MacBook with full disk after failed OS upgrade I tried to install the latest MacOS and the installation failed because there was no enough space. From there on every time I try log in to my account a status bar appears and then the whole system shuts down. Same thing happens in Safe mode. 

In recovery mode I tried a clean OS install but the wizard said that there is 0kB free on my disk. I imagine the installer from the previous upgrade attempt is still somewhere on my disk, taking up a lot of space. 

So I tried launching a terminal and deleting random unneeded files.

After having deleted probably between 500 and 1000 MB of data, I tried restarting and logging in, but the system shuts down at the same point in that login status bar. 

FileVault is enabled on my laptop. 

How can I recover my laptop?
There are a few good suggestions here. In the end the approach that solved my problem was starting recovery mode, and deleting a lot of unneeded files from my hard disk. 
(There was a lot of leftover stuff in Library/Application Support from applications that I have long ago uninstalled.)

After I freed up ~20GB of data, I could launch a reinstall of MacOS from recovery mode, which did the trick.