All the HTTP error codes are like that. There are hundreds of them, but they're not specific enough to actually tell you what went wrong without site-specific information.
Which is why REST APIs should just accept that the only two error codes that matter are 400 Your Fault and 500 My Fault. Too much ambiguity when you try to shoehorn meaning into responses like 401 and 404.
I assume it was some server session error because my friends weren't having the issue.
But the 418 was a useless error code to report.