Swedish to English Tech/Engineering Computers (general)

In reference to website design, seemingly, used to describe text shown when an error message comes up.

Introduction/preamble don't seem to fit, as I can't see what they would be introducing or preceding in the case. How much text can be associated with an error message?

Den ingress som visas för HTTP Statuskod 404, där inga sökförslag kan visas.

Den ingress som visas för HTTP Statuskod 404, där sökförslag kan visas.