RFC 5545 states that CRLF line breaks should be used but other consumer seems to allow CR being missing. https://datatracker.ietf.org/doc/html/rfc5545#section-3.1 Note, that the check result was ignored if the content-type is text/calendar. Part-of: <https://gitlab.gnome.org/GNOME/gnome-calendar/-/merge_requests/814>