gistfile1.txt

$ opam switch create 4.11 4.11.1

<><> Gathering sources ><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
[ocaml-base-compiler.4.11.1] downloaded from cache at https://opam.ocaml.org/cache

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
∗ installed base-bigarray.base
∗ installed base-threads.base
∗ installed base-unix.base
∗ installed ocaml-base-compiler.4.11.1
∗ installed ocaml-config.1
∗ installed ocaml.4.11.1
Done.
# Run eval $(opam env) to update the current shell environment
$ eval $(opam env)

$ opam pin ppx_deriving_yojson https://github.com/ocaml-ppx/ppx_deriving_yojson.git#3267547949b1a455264cb7ad6c9dd8e5a996f5e6
[ppx_deriving_yojson.3.5.3] synchronised from git+https://github.com/ocaml-ppx/ppx_deriving_yojson.git#3267547949b1a455264cb7ad6c9dd8e5a996f5e6
ppx_deriving_yojson is now pinned to git+https://github.com/ocaml-ppx/ppx_deriving_yojson.git#3267547949b1a455264cb7ad6c9dd8e5a996f5e6 (version 3.5.3)

Sorry, no solution found: there seems to be a problem with your request.

[NOTE] Pinning command successful, but your installed packages may be out of sync.

$ opam pin
ppx_deriving_yojson.3.5.3  (uninstalled)  git  git+https://github.com/ocaml-ppx/ppx_deriving_yojson.git#3267547949b1a455264cb7ad6c9dd8e5a996f5e6

$ opam install ppx_deriving_yojson 

<><> Synchronising pinned packages ><><><><><><><><><><><><><><><><><><><><><><>
[ppx_deriving_yojson.3.5.3] no changes from git+https://github.com/ocaml-ppx/ppx_deriving_yojson.git#3267547949b1a455264cb7ad6c9dd8e5a996f5e6

Sorry, no solution found: there seems to be a problem with your request.

No solution found, exiting