I was adding fields to an existing entity, and one field I accidentally made a money field rather than a float. So, I went back and deleted the field and recreated it as a float. No big deal. Well, it is a big deal if you have ever had multiple currencies in your system. All of a sudden, users were getting the infamous "Object reference not set to the instance of an object." error. I looked on the server and found that the error was coming from the following plugin:
That wasn't any plugin I had ever put on the server so I was surprised to see it. As it turns out, once a money field is added to an entity within a system that has ever utilized multiple currencies, there must ALWAYS be a money field on the form. Otherwise you get the above error. I tried deleting the extra currencies in the system to see if that would fix the problem; it didn't. I guess something changes once you add more than one currency that doesn't change back. I ended up in having to add a money field to the entity. I didn't put it on the form, and I'll never use any data from it, it's just there to prevent that error from popping up. Awesome.
Hopefully this helps someone else.
Dynamic Methods Inc.