I had installed merlin 6 months ago to be able to compile Ocaml and I had no problems. I have recently upgraded to update everything but it was impossible to make the package work.

When I try to reinstall it I get this error message (opam install -y merlin):

[coq-released] synchronised from https://coq.inria.fr/opam/released
[default] no changes from https://opam.ocaml.org
The following actions will be performed:
  ∗ install ocaml-base-compiler 4.12.0  [required by ocaml]
  ∗ install ocaml-config        2       [required by ocaml]
  ∗ install ocaml               4.12.0  [required by merlin]
  ∗ install ocamlfind           1.9.3   [required by dot-merlin-reader]
  ∗ install dune                2.9.3   [required by merlin]
  ∗ install result              1.5     [required by merlin]
  ∗ install easy-format         1.3.2   [required by yojson]
  ∗ install csexp               1.5.1   [required by merlin]
  ∗ install cppo                1.6.8   [required by yojson]
  ∗ install biniou              1.2.1   [required by yojson]
  ∗ install yojson              1.7.0   [required by merlin]
  ∗ install dot-merlin-reader   4.1     [required by merlin]
  ∗ install merlin              4.4-412
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