For anyone that works on music with a DAW (Digital Audio Workstation) or looper you will have no doubt used VSTs, VSTi's or plugins of some sort. Depending on what you want to call them. So for us dinosaurs - I started writing some music many moons ago on old software. Some of it has been updated. Other pieces of software have become extinct. I think most anyone who takes their music seriously wants their source files - in case they want to tweak anything, remix, or even just to generate instrumentals for live stuff. If you are a musician and you ever collaborate either in a studio or with other musicians. ALWAYS get the source files, stems and a or save files for the specific application that it was used in.
So one of the issues that I've faced is that I used a Sony Track EQ from Acid Music Studio 5.0 on a lot of Fruit Loops projects. This is an old 32 bit plugin. I actually own Sony Acid Pro 6. But Fruity Studio can't find the Track EQ if I install 6.0. It has to do with the software's name being changed from Acid Music Studio to Sony Acid Pro. So - anyhow - in trying to get everything compatible with the newer DAWs. There are a lot of issues. I have lots of old projects that I've never finished. I don't want to lose that stuff. Some of it is worth converting to newer project types. Some of it isn't. It is a lot of work.
The good news is I have been working on finishing more music. I've put more time into working on new material than I have in a long time. Some of what I'm working on has a learning curve where I need to re-learn something. Other stuff is like jumping into a comfy pair of pants from years ago. (fresh out the dryer of course)