[lostlogin]

A tricky one that I’ve seen cause harm is white space or otherwise invisible characters (eg line breaks).

Super frustratingly, Macs populating HL7 fields caused intense pain. It turns out that the character ’ when typed on a Mac keyboard is not compatible with all versions of HL7, or perhaps wasn’t compatible with what the HL7 was passed off to. It’s a distant memory now but it was words like o’clock versus o′clock, or something like that which broke radiology report distribution.

It went on for years before being caught.

Edit: HN is displaying the ’ differently to how it looks when I type it, but it’s still the same character. The fact that we couldn’t see the difference when debugging was half the problem, so this is quite funny.

[matsemann]

Encoding is hard. Recently had a problem where some proxy/load balancer (I think) in Go would crash, as it couldn't handle æøå in some headers which was returned from some service doing ip lookups before passing on the request. Which of course hit our workers in the city of Tønsberg.

Another example I remember from earlier days is the BOM in xml files. When it was wrong things could crash in all kind of weird ways, and impossible to see.