diff --git a/cmd/operator/main.go b/cmd/operator/main.go
index 7d9e0f0..becd92d 100644
--- a/cmd/operator/main.go
+++ b/cmd/operator/main.go
@@ -73,6 +73,13 @@ func main() {
 		os.Exit(1)
 	}
 
+	// Advisory only: warn (never exit) if the installed CRDs are missing or
+	// predate this operator's schema, which otherwise surfaces only as opaque
+	// strict-decode failures during reconcile.
+	crdCtx, crdCancel := context.WithTimeout(context.Background(), 15*time.Second)
+	controller.CheckCRDVersions(crdCtx, mgr.GetConfig())
+	crdCancel()
+
 	if err := mgr.AddHealthzCheck("healthz", healthz.Ping); err != nil {
 		logger.Error(err, "unable to set up health check")
 		os.Exit(1)
diff --git a/config/rbac/role.yaml b/config/rbac/role.yaml
index e705659..730177f 100644
--- a/config/rbac/role.yaml
+++ b/config/rbac/role.yaml
@@ -16,6 +16,13 @@ rules:
   - patch
   - update
   - watch
+- apiGroups:
+  - apiextensions.k8s.io
+  resources:
+  - customresourcedefinitions
+  verbs:
+  - get
+  - list
 - apiGroups:
   - ceph.unkin.net
   resources:
diff --git a/go.mod b/go.mod
index 0a7e64d..ae763cc 100644
--- a/go.mod
+++ b/go.mod
@@ -9,6 +9,7 @@ require (
 	github.com/aws/smithy-go v1.27.4
 	github.com/ceph/go-ceph v0.40.0
 	k8s.io/api v0.34.4
+	k8s.io/apiextensions-apiserver v0.34.1
 	k8s.io/apimachinery v0.34.4
 	k8s.io/client-go v0.34.4
 	sigs.k8s.io/controller-runtime v0.22.4
@@ -70,7 +71,6 @@ require (
 	gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
-	k8s.io/apiextensions-apiserver v0.34.1 // indirect
 	k8s.io/klog/v2 v2.130.1 // indirect
 	k8s.io/kube-openapi v0.0.0-20250710124328-f3f2b991d03b // indirect
 	k8s.io/utils v0.0.0-20250604170112-4c0f3b243397 // indirect
diff --git a/internal/controller/crdcheck.go b/internal/controller/crdcheck.go
new file mode 100644
index 0000000..6f6d689
--- /dev/null
+++ b/internal/controller/crdcheck.go
@@ -0,0 +1,89 @@
+package controller
+
+import (
+	"context"
+
+	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
+	apiextensionsclient "k8s.io/apiextensions-apiserver/pkg/client/clientset/clientset"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/rest"
+	ctrl "sigs.k8s.io/controller-runtime"
+)
+
+// The CRD version check reads CustomResourceDefinitions to compare the
+// installed schema against what this operator expects.
+//
+// +kubebuilder:rbac:groups=apiextensions.k8s.io,resources=customresourcedefinitions,verbs=get;list
+
+// crdSentinel names a CRD and a spec property that only exists in the schema
+// version shipped alongside this operator build. If the installed CRD lacks the
+// sentinel, its schema predates this operator and strict decoding of new spec
+// fields will silently fail. Keep this list in one place so new fields are easy
+// to register as sentinels.
+type crdSentinel struct {
+	// crd is the metadata.name of the CustomResourceDefinition.
+	crd string
+	// specProperty is a key expected under
+	// .spec.versions[].schema.openAPIV3Schema.properties.spec.properties.
+	specProperty string
+}
+
+// crdSentinels is the authoritative list checked at startup. Extend it whenever
+// a new spec field is added that older CRDs would reject.
+var crdSentinels = []crdSentinel{
+	{crd: "buckets.ceph.unkin.net", specProperty: "managePolicy"},
+	{crd: "objectstoreusers.ceph.unkin.net", specProperty: "retainOnDelete"},
+	{crd: "bucketaccesses.ceph.unkin.net", specProperty: "rawStatements"},
+}
+
+// CheckCRDVersions verifies that every CRD this operator owns is installed and
+// carries the schema fields this build expects. It is advisory only: it logs a
+// distinct WARNING per problem and never returns an error or exits, so a stale
+// or missing CRD cannot block startup.
+func CheckCRDVersions(ctx context.Context, cfg *rest.Config) {
+	log := ctrl.Log.WithName("crd-version-check")
+
+	client, err := apiextensionsclient.NewForConfig(cfg)
+	if err != nil {
+		log.Error(err, "unable to build apiextensions client; skipping CRD version check")
+		return
+	}
+
+	for _, s := range crdSentinels {
+		crd, err := client.ApiextensionsV1().CustomResourceDefinitions().Get(ctx, s.crd, metav1.GetOptions{})
+		if apierrors.IsNotFound(err) {
+			log.Info("WARNING: CRD is not installed — apply the CRDs matching this operator version",
+				"crd", s.crd)
+			continue
+		}
+		if err != nil {
+			log.Error(err, "unable to read CRD; cannot verify it matches this operator version",
+				"crd", s.crd)
+			continue
+		}
+		if !crdHasSpecProperty(crd, s.specProperty) {
+			log.Info("WARNING: CRD is out of date — apply the CRDs matching this operator version",
+				"crd", s.crd, "missingField", "spec."+s.specProperty)
+		}
+	}
+}
+
+// crdHasSpecProperty reports whether any served/stored version of the CRD
+// declares the given property under spec.
+func crdHasSpecProperty(crd *apiextensionsv1.CustomResourceDefinition, property string) bool {
+	for _, v := range crd.Spec.Versions {
+		schema := v.Schema
+		if schema == nil || schema.OpenAPIV3Schema == nil {
+			continue
+		}
+		specSchema, ok := schema.OpenAPIV3Schema.Properties["spec"]
+		if !ok {
+			continue
+		}
+		if _, ok := specSchema.Properties[property]; ok {
+			return true
+		}
+	}
+	return false
+}