EHM The Blue Line

I got this Error notification when trying to load up a save where I used a database that heavily modified the Finnish league structure (promotions, relegations and extra levels below Suomi-sarja). Has anyone encountered it before? If so how to fix it?

I don't know how to fix it. I would suggest reverting to the unmodified database and then making your changes incrementally before testing. That way, you will be able to narrow down the source of the issue.