So, in opam I've hit this problem - I need a package, but it's requirements
conflict with another package that I have. Just typing opam install
the_package will fail with "No package matches the_package". the_package is
async_core

I used the cudf solver farm remotely after hunting  the bug, but as far as
this goes, I don't know what to do because I don't have control over those
packages or their versions. I can maybe update my version of core (if the
upgrade is compatible with a package that I have that uses it).

Any advise for the error below?


The following dependencies couldn't be met:
  - async_core -> core = 109.35.00 | core = 109.36.00 | core = 109.37.00 |
core = 109.38.00 | core = 109.40.00 | core = 109.41.00 | core = 109.42.00 |
core = 109.45.00 | core = 109.47.00 | core = 109.53.01 | core =
<unavailable version> | core < 109.31.00 | core <= 109.31.00 -> pa_test =
109.53.00 -> core_kernel < 111.25.00
  - async_core -> core = 109.35.00 | core = 109.36.00 | core = 109.37.00 |
core = 109.38.00 | core = 109.40.00 | core = 109.41.00 | core = 109.42.00 |
core = 109.45.00 | core = 109.47.00 | core = 109.53.01 | core =
<unavailable version> | core < 109.31.00 | core <= 109.31.00 ->
custom_printf = <unavailable version>
  - async_core -> pa_test = 109.53.00 | pa_test <= 109.53.02 -> core_kernel
= <unavailable version> | core_kernel < 111.25.00
  - async_core -> zero = 109.21.00 -> core < 109.31.00
Your request can't be satisfied:
  - No package matches core.<unavailable version>.
  - No package matches core_kernel.<unavailable version>.
  - No package matches custom_printf.<unavailable version>.
  - core<109.31.00 is not available because it requires OCaml >= 4.00.1 & <
4.01.0.
  - core_kernel<111.25.00 is not available because it requires OCaml >=
4.01.0 & < 4.02.1.

No solution found, exiting