The Vietnam Grand Prix has been cancelled after an official has been arrested for corruption charges.
https://www.bbc.co.uk/sport/formula1/54879815
Must be pretty bad considering the company that is kept on the calendar (Russia, China, Saudi etc). Not that I'm saying those grand prix are corrupt, but historically those countries have played a little bit fast and loose with corruption.
Shame about all the money spent designing and building the Vietnam track and how it was touted as 'designed with overtaking in mind' (Ross Brawn's words I believe).