Error when voting

I tried to upvote this comment:

https://fedia.io/m/Brussels/t/1145402/Delhaize-and-Intermarche-loyalty-more-intrusive-than-Colruyt-but-Colruyt/comment/7061005#entry-comment-7061005

Got a page that simply said “Error”. That’s it. Not internal server error or a 500 error.. just “error”. Thought it’s worth mention since it’s possibly the first time I've seen such a generic and info-deprived error msg.