Why do I get this Error Message: An active default article for Event charges has not been configured in Property Settings?

This error shows up, if there is no default Article configured for Events. To set this up, please go to Administration > Property and scroll down to 'Property Settings'. Here is where you can set default Articles for various things, including Events. Please add an article in there, scroll down and press 'Update Settings' to save your changes and the issue will then be resolved.