I observed this error in my dev environment (cluster nearly 500 days old) when trying the dev branch from !6897: on `alertmanager-config` Kustomization, in status: ``` status: conditions: - lastTransitionTime: "2026-03-18T09:40:04Z" message: Detecting drift for revision revisit-force-reconcile@sha1:b9f286f12bd9d812f11edc12da6088b8bd4f8117 with a timeout of 30s observedGeneration: 876 reason: ProgressingWithRetry status: "True" type: Reconciling - lastTransitionTime: "2026-03-18T09:40:04Z" message: | HelmRelease/sylva-system/alertmanager-config dry-run failed: failed to prune fields: failed add back owned items: failed to convert merged object at version helm.toolkit.fluxcd.io/v2beta2: errors: .spec.install.strategy: field not declared in schema .spec.upgrade.strategy: field not declared in schema observedGeneration: 876 reason: ReconciliationFailed status: "False" type: Ready ``` The problem is non-obvious because: * my MR is introducing the use of field added to HelmReleases in Flux 2.7, on the v2 apiVersion * the Kustomization is producing manifests in that version (we've had v2 for a long time in Sylva) ;`flux build kustomization alertmanager-config --path ./kustomize-units/helmrelease-generic` confirms that the Kustomization produces a v2. **The mention of `v2beta2` HelmRelease in the error is particularly surprising.** Looking closer, the HelmRelease has a trace of v2beta2 in fieldManagers: ```yaml apiVersion: helm.toolkit.fluxcd.io/v2 kind: HelmRelease metadata: annotations: reconcile.fluxcd.io/forceAt: "2025-07-31T10:02:11.571821656+02:00" reconcile.fluxcd.io/requestedAt: 2026-03-17T09:01:28 sylva-units-helm-revision: "890" sylvactl/reconcileCompletedAt.579.xGyftc: 2026-03-11T14:28:11 sylvactl/reconcileCompletedAt.580.W9JAml: 2026-03-12T08:29:19 sylvactl/reconcileCompletedAt.581.sGvych: 2026-03-13T14:11:40 sylvactl/reconcileCompletedAt.583.zaidgM: 2026-03-16T12:46:52 sylvactl/reconcileCompletedAt.584.LNBb9z: 2026-03-17T09:01:29 sylvactl/reconcileStartedAt.579.xGyftc: 2026-03-11T14:28:10 sylvactl/reconcileStartedAt.580.W9JAml: 2026-03-12T08:29:19 sylvactl/reconcileStartedAt.581.sGvych: 2026-03-13T14:11:40 sylvactl/reconcileStartedAt.583.zaidgM: 2026-03-16T12:46:52 sylvactl/reconcileStartedAt.584.LNBb9z: 2026-03-17T09:01:28 creationTimestamp: "2024-11-12T15:36:31Z" #... managedFields: # ... - apiVersion: helm.toolkit.fluxcd.io/v2beta2 fieldsType: FieldsV1 fieldsV1: f:metadata: f:annotations: {} manager: sylvactl operation: Update time: "2025-03-20T09:03:36Z" # ... - apiVersion: helm.toolkit.fluxcd.io/v2 fieldsType: FieldsV1 fieldsV1: f:metadata: f:annotations: f:reconcile.fluxcd.io/requestedAt: {} f:sylvactl/reconcileCompletedAt.579.xGyftc: {} f:sylvactl/reconcileCompletedAt.580.W9JAml: {} f:sylvactl/reconcileCompletedAt.581.sGvych: {} f:sylvactl/reconcileCompletedAt.583.zaidgM: {} f:sylvactl/reconcileCompletedAt.584.LNBb9z: {} f:sylvactl/reconcileStartedAt.579.xGyftc: {} f:sylvactl/reconcileStartedAt.580.W9JAml: {} f:sylvactl/reconcileStartedAt.581.sGvych: {} f:sylvactl/reconcileStartedAt.583.zaidgM: {} f:sylvactl/reconcileStartedAt.584.LNBb9z: {} manager: sylvactl operation: Update time: "2026-03-17T09:01:29Z" ``` We have in fact twice the `sylvactl` field manager, once from a long time ago with the old `apiVersion: v2beta2` and a recent one with the new one. And it seems that the SSA logic on which the kustomize-controller relies does not support this combination well. I tried to see if running `flux migrate` would solve the problem, and it did. After running it: * no trace of the old field manager (presumably merged with the new one) * the Kustomization reconciled the HelmRelease successfully **Conclusions**: * we should run `flux migrate` as part of a `kube-job` after flux-system major upgrade * we may have the same issue when the kustomize-controller tries to update any other CR that would be in that situation where an old field manager remains using an older apiVersion