I'm in the process of a little bit of VPS reorganizing. My current contract is running out in May, so I called up my provider and asked if I could change from a yearly contract to a monthly one. They said yes, but only if you upgrade, which I didn't really want to do. I'm already only using a small portion of my available resources. So instead I cancelled the old one and ordered a new one (with the same provider.) I ordered it early so that I could move everything from the old VPS to the the new one at leisure, and also so that I can move files from one VPS to the other directly instead of over my DSL connection.
My provider offers a free key for Plesk with their server deals. I didn't try it before, because you have to do a complete server re-install and choose OS+Plesk - the default installation is Ubuntu 16.04 without Plesk, and by the time I wanted to try and realized that I would have to start over I had already put way too much work in. So I figured with the new VPS, I'll give it a shot. I went to the "new installation" section of my server admin backend and chose Ubuntu 18.04 with Plesk Onyx. When it was done, I logged in, installed tasksel, ran it, and noticed that "mail server" was checked. I thought it was odd, but didn't bother to do any research. I removed it, checked "lamp server", hit OK and promptly got an error. Apparently, Plesk depends on the mail server packages. After that tasksel wouldn't let me install the lamp-server anymore, not even with leaving the mail server in place.
apt install -f also produced error messages, so I decided to not bother and start over right away.
I don't think I ever screwed up a system quite that quickly. The only thing I had done at that point was to upload my SSH identity and configure the SSH server. It's good, though, that it happened right away. I'm currently re-installing Ubuntu - minus Plesk. Haven't needed it in almost a year, I can keep doing without it.