Error installing tezos-crypto

Question

I am trying to install the library tezos-crypto using Opam on Kubuntu 20.04. I am getting the following error:

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
[ERROR] The compilation of tezos-stdlib-unix failed at "/home/marc/.opam/opam-init/hooks/sandbox.sh build dune build -p
        tezos-stdlib-unix -j 15".

#=== ERROR while compiling tezos-stdlib-unix.10.2 =============================#
# context     2.0.5 | linux/x86_64 | ocaml-base-compiler.4.11.1 | https://opam.ocaml.org#e0171a79
# path        ~/.opam/default/.opam-switch/build/tezos-stdlib-unix.10.2
# command     ~/.opam/opam-init/hooks/sandbox.sh build dune build -p tezos-stdlib-unix -j 15
# exit-code   1
# env-file    ~/.opam/log/tezos-stdlib-unix-69301-e0ba4f.env
# output-file ~/.opam/log/tezos-stdlib-unix-69301-e0ba4f.out
### output ###
# [...]
# (cd _build/default && /home/marc/.opam/default/bin/ocamlc.opt -w -40 -open Tezos_error_monad -open Tezos_error_monad.TzLwtreslib -open Tezos_event_logging -open Tezos_stdlib -open Data_encoding -g -bin-annot -I src/lib_stdlib_unix/.tezos_stdlib_unix.objs/byte -I /home/marc/.opam/default/lib/angstrom -I /home/marc/.opam/default/lib/astring -I /home/marc/.opam/default/lib/base -I /home/marc/.op[...]
# File "src/lib_stdlib_unix/file_descriptor_sink.ml", line 116, characters 16-24:
# 116 |                 Fmt.strf "%s-%d%s" chopped (Unix.getpid ()) ext
#                       ^^^^^^^^
# Alert deprecated: Fmt.strf
# use Fmt.str instead.
# (cd _build/default && /home/marc/.opam/default/bin/ocamlopt.opt -w -40 -open Tezos_error_monad -open Tezos_error_monad.TzLwtreslib -open Tezos_event_logging -open Tezos_stdlib -open Data_encoding -g -I src/lib_stdlib_unix/.tezos_stdlib_unix.objs/byte -I src/lib_stdlib_unix/.tezos_stdlib_unix.objs/native -I /home/marc/.opam/default/lib/angstrom -I /home/marc/.opam/default/lib/astring -I /home/[...]
# File "src/lib_stdlib_unix/file_descriptor_sink.ml", line 116, characters 16-24:
# 116 |                 Fmt.strf "%s-%d%s" chopped (Unix.getpid ()) ext
#                       ^^^^^^^^
# Alert deprecated: Fmt.strf
# use Fmt.str instead.



<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
┌─ The following actions failed
│ λ build tezos-stdlib-unix 10.2
└─ 
╶─ No changes have been performed

Answer 1

Because you are in an opam "switch" that uses an old version of the OCaml compiler (4.11.1), you are trying to install the most recent version of tezos-crypto compatible with this compiler which is an old version (10.2).(Probably, this version is not compatible with a version of the fmt library that has been released more recently than tezos-crypto.10.2 and no "upper bound" has been specified in the set of version constraints).

By using the current version of the OCaml compiler used by Octez (4.14.*), you should be able to install the latest version of tezos-crypto (15.1) which hopefully compiles fine.