ENOSPC = random things go wrong.

There are many synonyms for ENOSPC, like "disk full", "space storage full", "space storage exhausted", "no more space left on device", and those other repulsive errors. For the sake of simplicity, I am going to refer to it as ENOSPC.

If you are in this condition on the operating system partition, get out of it quickly or random things will go wrong. Text editors which write directly to a text file rather than creating a temporary file and then replacing the text file could end up blanking the text file, softwares' configuration files might fail saving which causes a reset, and web browsers might spontaneously reset cookies and lose history.

For example, Firefox has created a gap in the web browsing history, as shown here. The history that is now memory-holed initially appeared to have been recorded successfully. Apparently, a failed write to the places.sqlite database when closing the browser created this gap.