3.23.0 release tracker

[shonfeder]

Target release date: Monday, 2026-04-20 approx. 17:00CET/13:00 Eastern

Known blockers

Issues blocking the release

• issue OxCaml Trunk CI job fails on diff including uncexpected version field #14214 blocking the release because we are committed to ensuring compatibility with oxcaml in future release (to the best of our ability)
  • resolved by PR chore: replace revdeps-dev-build workflow with a full nix derivation #14228
• Avoid @install in make release #14270 breaking the nightly builds

Preparation

To begin once all initial blockers are resolved.

• Run pre-release CI jobs on main branch
  • mirage
  • packaging
• Work thru the pre-release phase.
  Alpha release PRs into opam repo:
  • [link to OPAM PR 1]
  • [link to OPAM PR 2]

Release

• Work thru the release phase.
• opam repo publication PR [link to opam PR]

Post-release

• Merge release branch into main

• Write a post about the release on Discuss: [link]

• Open PR announcing release on ocaml.org: [link]

• Store the revdeps error file in the logs as HTML

• Increase the version of Dune to the new latest minor version

  • in the CI workflow
  • in dune-project
  • in the dune-rpc

[Alizter]

First blocker

• Sandboxed (package) deps are broken #14213

It has a reproduction case, but I am trying to finish up a feature #14200 in order to express what I need for the reproduction case first.

[Alizter]

This should fix the build of ocaml-lsp

• refactor: stop using Stdune.Time.t in registry #14221

[rgrinberg]

You don't necessarily need to bump the dune version in dune's own dune-project. This is done on a by-need basis whenever we need to use the latest feature in dune for building dune itself.

[Alizter]

On closer inspection, the issue #14213 doesn't quite fall into regression territory since the only reproduction case I am able to produce relies on internal implementation details of dune and nothing purposefully user facing.

I've therefore closed this issue.

However I would recommend you cut a new release branch since there have been 3.23. additions since the last branch point and other bug fixes too.

[shonfeder]

The nightly builds are failing with opam generation errors:

building '/nix/store/x5mymj6zqx3cnf2n35hk0yrc1b43744f-dune-3.x-n-a.drv'...
error: Cannot build '/nix/store/x5mymj6zqx3cnf2n35hk0yrc1b43744f-dune-3.x-n-a.drv'.
       Reason: builder failed with exit code 2.
       Output paths:
         /nix/store/cmbf056v7ni2wqw00np9bkk81zy6rlpd-dune-3.x-n-a
       Last 25 log lines:
       > patching script interpreter paths in ./configure
       > ./configure: interpreter directive changed from "#!/bin/sh" to "/nix/store/s0psayl7zvkvwdcqc8fy1sbv8rlf1yq8-bash-5.3p9/bin/sh"
       > configure flags: ''
       > Running phase: buildPhase
       > build flags: SHELL=/nix/store/s0psayl7zvkvwdcqc8fy1sbv8rlf1yq8-bash-5.3p9/bin/bash release
       > ocamllex -q -o boot/pps.ml boot/pps.mll
       > ocamlc -output-complete-exe -intf-suffix .dummy -g -o .duneboot.exe -I boot -I +unix unix.cma boot/pps.ml boot/types.ml boot/libs.ml boot/duneboot.ml
       > ./.duneboot.exe
       > Warning: Cache directories could not be created: Read-only file system;
       > disabling cache
       > Hint: Make sure the directory /homeless-shelter/.cache/dune/db/temp can be
       > created
       > File "opam/dune.opam", line 1, characters 0-0:
       > (cd _build/default && /nix/store/hrkhhbx6v8fzwnizwvqh9h0yff5vcp75-diffutils-3.12/bin/diff -u --label opam/dune.opam --label opam/dune.opam.generated opam/dune.opam opam/dune.opam.generated)
       > --- opam/dune.opam
       > +++ opam/dune.opam.generated
       > @@ -1,5 +1,7 @@
       >  # This file is generated by dune, edit dune-project instead
       >  opam-version: "2.0"
       > +version:
       > +  "Nightly build 2026-04-20T04:17:47Z, git revision 4ce282c9c83413c2133d034d843ac816c6beb7dd"
       >  synopsis: "Fast, portable, and opinionated build system"
       >  description: """
       >
       > make: *** [Makefile:40: release] Error 1
       For full logs, run:
         nix log /nix/store/x5mymj6zqx3cnf2n35hk0yrc1b43744f-dune-3.x-n-a.drv

This appears to be the same issue as #14214 This is apparently due to #14108

Since two of our own CI jobs have failed with this, I expect we are likely to break the CI of plenty of other folks too. IIUC from the motivating PR, this should be gated by the dune lang version, so this will only impact people when they update to 3.23. So long as we flag this in the announcement, I think we should be fine to release as is.

[Alizter]

This only affects dune packages and together with @Leonidas-from-XIV we have #14270 that fixes that particular issue. Please allow for that to be merged and then recut.

[Leonidas-from-XIV]

#14270 has been merged and fixes the nightly builds.