Juju 4.0.3

🗓️ 4 Mar 2026

🎯 Highlights

• 4.0.3 is the cumulative patch release from 4.0.1 to 4.0.3: 4.0.2 was not promoted, so this release carries the full stability and migration work from both patch versions.

• Model migration coverage expands significantly: Juju model config, machines, subnets, filesystems, volumes, and storage attachments imports have all been reworked.

• CMR reliability improves end-to-end: importing remote consumers/offerers, relation units, and duplicate remote applications is now safer and more consistent.

• Storage and object-store behavior is more robust under load: fixes target retries, leaked readers, spin-lock behavior, and deletion safety for de-duplicated blobs.

• Lifecycle and operator UX is tightened up: better removal ordering and foreign key (FK) cleanup, clearer action error output, and more accurate offer visibility.

⚠️ Breaking changes

N/A.

• Upgrade note: transition behavior for storage and offers is now explicitly documented; migrating models with multiple SAAS entries for one offer may collapse to a single SAAS entry. feat: add transition information for storage and offers

🚀 Features (key changes)

N/A. This is a patch release focused on migration completeness, reliability, and operational correctness rather than new top-level product features.

Key changes include:

• Model migration now imports storage attachments with storage instances: attachment records are imported as part of the same storage migration flow. feat: import storage attachments alongside storage instances

• CMR migration merges duplicate remote applications: duplicate remote applications are now merged during import. feat: merging duplicate remote applications

• Storage listing works through the client facade: storage instances, filesystems, and volumes are listed through the storage client path. feat: storage list client

• network-get supports providers without spaces: networking data is now returned correctly for providers that do not implement space support. fix: network-get for providers without space support

Full cumulative list of changes: https://github.com/juju/juju/compare/v4.0.1…v4.0.3

🛠️ Fixes

🔁 Migration/CMR correctness

• feat: allow model migration to be reentrant

• fix: relation unit watcher for remote app with no units

• fix: ensure we watch all relation units

• fix: nil pointer panics during caas migration

• fix(remoterelationconsumer): clean up orphaned offer_connection when local relation is removed during registration

🗃️ Object store, resources, and firewaller stability

• fix: prevent getting empty resources

• fix: only delete unreferenced objects from store

• fix: close all file object store readers

• fix: prevent spin-lock in object store scoped context

• fix: retries and not found errors in the remote objectstore

• feat: handle firewaller duplicate changes

🧱 Lifecycle, offers, and cloud lifecycle safety

• fix(removal): clean up FK references on app, unit, and relation delete

• fix(cloud): cascade credential deletion when removing a cloud

• fix(offers): show correct list of users in show-offer command

• fix(offer): use charm reference_name instead of metadata name in v_offer_detail view

• fix(actions): show correct message when task has error outcome

📘 Summary

4.0.3 is a reliability-focused release: it finishes major chunks of the 3.6→4.0 migration path, hardens CMR and storage/object-store behavior in real workloads, and improves day-2 operator visibility and lifecycle safety across offers, actions, and cloud cleanup workflows.