We have updated our Community Code of Conduct. Please read through the new rules for the forum that are an integral part of Paradox Interactive’s User Agreement.
You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
Started a new game with the lastest patch (2.2.1 checksum DPOO) to test it out. Discovered a bug where a castle was built by the AI in a county that has 1 barony, 1 bishopric, and no cities.
I found out what must have happened, he first built a castle then using the decision to upgrade a tribal holding (with a fully upgraded hillfort) to a castle. This is unlikely to be changed for now.