Hi, maybe you deleted the administrator user?
To fix the error there has to be a user in the database whose ID is the same as the 'created_by_id' column of the first row in the 'og_companies' table, which I think has to be equal to 1. So if you don't have a user with an ID of 1 give that ID to some user and put that value to the created_by_id field of the owner company.