<< FIXED / SOLVED >>
This is a vague error and I have tried over a dozen times to not get the generic error.
Problem 1: First I tried to register as a company but my DUNS code was invalid because I have a sole proprietorship.
Solution 1: By enrolling as an individual.
Problem 2: I got the following generic error:
Solution 2: You had to fill in 2 addresses (name, city etc.) and then you had to either fill in another address field (also name, city etc.) OR check the checkbox so you didn't have to fill everything in twice. I tried the checkbox thing first which resulted in the error above. If you uncheck the checkbox and fill in the second set of address information then it will let you continue. This solved it for me.
Note that are apparently a few reasons why you can get this error, but this solved it for me. Good luck!
Kind regards,
Matthijs
www.essenburgmultimedia.nl