Package fat-filesystem

Failed to find a solution:

no platform:
2025-05-16 17:28.37 [INFO] Solving for ocaml-base-compiler,
                           fat-filesystem, constraints ocaml-base-compiler<=5.3.0,
                           fat-filesystem=0.15.0 using opam_repository_commit cf409d95af00ff822422bd76b657ed213b661401

2025-05-16 17:28.38 [INFO] base: eliminated all possibilities in 0.60 s

2025-05-16 17:28.38 [INFO] = base =

2025-05-16 17:28.38 [INFO] Can't find all required versions.
Selected: astring.0.8.5 base-bytes.base base-threads.base base-unix.base
          cmdliner.1.3.0 conf-pkg-config.4 cppo.1.8.0 csexp.1.5.2
          cstruct.6.2.0 dune.3.18.2 dune-configurator.3.18.2 fmt.0.10.0
          io-page.3.0.0 lwt.5.9.1 mirage-block.3.0.2 num.1.5-1 ocaml.5.5.0
          ocaml-config.3 ocaml-options-vanilla.1 ocamlbuild.0.16.1
          ocamlfind.1.9.8 ocplib-endian.1.2 parsexp.v0.17.0 ppx_cstruct.6.2.0
          re.1.12.0 rresult.0.7.0 seq.base sexplib.v0.17.0 sexplib0.v0.17.0
          topkg.1.0.8 fat-filesystem&ocaml-base-compiler ocaml-variants
          ocaml-base-compiler ocaml-base-compiler
- fat-filesystem -> fat-filesystem.0.15.0
    User requested = 0.15.0
- io-page-unix -> (problem)
    No usable implementations:
      io-page-unix.2.3.0: Availability condition not satisfied
      io-page-unix.2.2.0: Availability condition not satisfied
      io-page-unix.2.1.0: Availability condition not satisfied
      io-page-unix.2.0.1: Availability condition not satisfied
      io-page-unix.2.0.0: Availability condition not satisfied
- mirage-block-unix -> (problem)
    fat-filesystem 0.15.0 requires >= 2.5.0 & < 2.13.0
    Rejected candidates:
      mirage-block-unix.2.14.2: Incompatible with restriction: >= 2.5.0 & < 2.13.0
      mirage-block-unix.2.14.1: Incompatible with restriction: >= 2.5.0 & < 2.13.0
      mirage-block-unix.2.14.0: Incompatible with restriction: >= 2.5.0 & < 2.13.0
      mirage-block-unix.2.13.0: Incompatible with restriction: >= 2.5.0 & < 2.13.0
      mirage-block-unix.2.12.1: Requires ocaml >= 4.06.0 & < 5.0
      ...
- mirage-kv -> mirage-kv.4.0.1
    fat-filesystem 0.15.0 requires < 5.0.0
- ocaml-base-compiler -> ocaml-base-compiler.5.3.0
    User requested <= 5.3.0
- ocaml-compiler -> (problem)
    ocaml-base-compiler 5.3.0 requires = 5.3.0
    Rejected candidates:
      ocaml-compiler.5.5: Incompatible with restriction: = 5.3.0
      ocaml-compiler.5.4: Incompatible with restriction: = 5.3.0
      ocaml-compiler.5.3.0: Requires ocaml = 5.3.0
      ocaml-compiler.5.3.0~rc1: Incompatible with restriction: = 5.3.0
      ocaml-compiler.5.3.0~beta2: Incompatible with restriction: = 5.3.0
      ...
- ocaml-variants -> (problem)
    Rejected candidates:
      ocaml-variants.5.5.0+trunk: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.4.0+trunk: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.3.1+trunk: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.3.0+options: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.3.0+BER: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ...
- ppxlib -> (problem)
    ppx_cstruct 6.2.0 requires >= 0.16.0
    Rejected candidates:
      ppxlib.0.36.0: Requires ocaml >= 4.08.0 & < 5.4.0
      ppxlib.0.35.0: Requires ocaml >= 4.08.0 & < 5.4.0
      ppxlib.0.34.0: Requires ocaml >= 4.04.1 & < 5.4.0
      ppxlib.0.33.0: Requires ocaml >= 4.04.1 & < 5.3.0
      ppxlib.0.32.1: Requires ocaml >= 4.04.1 & < 5.3.0
      ...