I’ve worked with some pretty rotten software, but management software is easily the most user unfriendly, so my vote goes to HPSM.
Due to really dumb requirements we had an app that used Python, Visual basic, C and C++, MATLAB, R and JavaScript. I’m not describing an application stack. This was a single binary. The amalgamation was so disturbing that it couldn’t even shut down once run, instead asking the operating system to please, please kill me.
Part of the installation procedure involves disabling all SSL certificate verification on company machines.
I mean, that sounds completely horrible, but it says something about the world of web, when it is not that different than any regular frontent/backend web stack. I.e. HTML + CSS + javascript + backend language + sql + random shit on top of it, all in the single project. And that’s even before talking about native apps for mobile.