Dear OCaml users, A regression has been discovered within OCaml 4.13.0 that make the compiler crash on classes named `row` module M = struct class row = object end end due to a collision between two families of internal identifiers. To restore your freedom to name classes however you want, we have released OCaml 4.13.1 as an early bug-fix release. This new version is available as a set of OPAM switches with opam update opam switch create 4.13.1 and as a source download here: https://caml.inria.fr/pub/distrib/ocaml-4.13 Happy hacking, Florian Angeletti for the OCaml team. OCaml 4.13.1 (01 October 2021) ------------------------------------------- ### Bug fixes - #10661, #10662: fix a bug with classes named "row" (Gabriel Scherer, report and review by Nicolás Ojeda Bär)