I didn't want to open this, but Google couldn't help me.
I remember seeing this scary long word during programming presentation in Hamburg and I it translates to fear of major version update. I though that it was common knowledge for German developers, but I was wrong.
Still, it was presented to me in this way, so I keep insisting on finding the answer.
One major clue is that is starts with Haupt. The idea behind the word is that developers are scared of breaking changes, so they would do anything to decline or postpone any major updates of their software.