diff --git a/crates/ecstore/src/core/pools.rs b/crates/ecstore/src/core/pools.rs
index bec66d9fe..e86d7c583 100644
--- a/crates/ecstore/src/core/pools.rs
+++ b/crates/ecstore/src/core/pools.rs
@@ -2640,8 +2640,12 @@ fn determine_decommission_final_state(items_failed: usize, was_cancelled: bool)
     }
 }
 
-fn decommission_remaining_version_count(total_versions: usize, expired: usize) -> usize {
-    total_versions.saturating_sub(expired)
+fn decommission_remaining_version_count(versions: &[rustfs_filemeta::FileInfo], expired: usize) -> usize {
+    versions
+        .iter()
+        .filter(|version| !version.tier_free_version())
+        .count()
+        .saturating_sub(expired)
 }
 
 fn should_skip_decommission_delete_marker(
@@ -3954,7 +3958,7 @@ impl ECStore {
                 continue;
             }
 
-            let remaining_versions = decommission_remaining_version_count(fivs.versions.len(), expired);
+            let remaining_versions = decommission_remaining_version_count(&fivs.versions, expired);
             if should_skip_decommission_delete_marker(version, remaining_versions, replication_config.is_some()) {
                 //
                 decommissioned += 1;
@@ -4419,6 +4423,39 @@ impl ECStore {
         .await
     }
 
+    #[cfg(test)]
+    pub(crate) async fn decommission_entry_for_test_with_bucket_incarnation(
+        self: &Arc<Self>,
+        idx: usize,
+        entry: MetaCacheEntry,
+        bucket: String,
+        set: Arc<SetDisks>,
+    ) -> Result<()> {
+        let expected_bucket_incarnation_id = if is_meta_bucketname(&bucket) {
+            None
+        } else {
+            Some(self.bucket_incarnation_id_from_disk(&bucket).await?)
+        };
+        self.decommission_entry(
+            CancellationToken::new(),
+            idx,
+            OffsetDateTime::now_utc(),
+            entry,
+            bucket,
+            set,
+            None,
+            None,
+            None,
+            expected_bucket_incarnation_id,
+        )
+        .await
+    }
+
+    #[cfg(test)]
+    pub(crate) async fn check_after_decommission_for_test(self: &Arc<Self>, idx: usize) -> Result<()> {
+        self.check_after_decommission(idx).await
+    }
+
     #[tracing::instrument(skip(self, rx))]
     async fn decommission_pool(
         self: &Arc<Self>,
@@ -5459,13 +5496,6 @@ mod tests {
         assert_eq!(determine_decommission_final_state(0, true), DecommissionFinalState::Failed);
     }
 
-    #[test]
-    fn decommission_remaining_version_count_excludes_only_expired_versions() {
-        assert_eq!(decommission_remaining_version_count(1, 0), 1);
-        assert_eq!(decommission_remaining_version_count(2, 1), 1);
-        assert_eq!(decommission_remaining_version_count(1, 1), 0);
-    }
-
     #[test]
     fn lifecycle_action_removes_data_movement_version_rejects_delete_marker_action() {
         assert!(!lifecycle_action_removes_data_movement_version(IlmAction::DeleteAction));
diff --git a/crates/ecstore/src/set_disk/mod.rs b/crates/ecstore/src/set_disk/mod.rs
index 4f73627e7..f5bb563a4 100644
--- a/crates/ecstore/src/set_disk/mod.rs
+++ b/crates/ecstore/src/set_disk/mod.rs
@@ -227,6 +227,44 @@ pub(super) fn restore_commit_operation_id_from_metadata(metadata: &HashMap<Strin
     restore_operation_id_from_metadata(metadata)
 }
 
+async fn check_decommission_tier_free_version_target(
+    disk: &DiskStore,
+    bucket: &str,
+    object: &str,
+    source: &FileInfo,
+) -> Result<()> {
+    let raw = match disk.read_xl(bucket, object, false).await {
+        Ok(raw) => raw,
+        Err(DiskError::FileNotFound | DiskError::FileVersionNotFound | DiskError::VolumeNotFound) => return Ok(()),
+        Err(err) => return Err(err.into()),
+    };
+    let meta = FileMeta::load(&raw.buf)?;
+    let source_version_id = source.version_id.filter(|version_id| !version_id.is_nil());
+    let mut matching_count = 0;
+    let mut all_matching_versions_equivalent = true;
+    for existing in meta
+        .versions
+        .iter()
+        .filter(|version| version.header.version_id.filter(|version_id| !version_id.is_nil()) == source_version_id)
+    {
+        matching_count += 1;
+        let existing = existing.into_fileinfo(bucket, object, true)?;
+        if !existing.tier_free_version() || !crate::store::object::tiered_data_movement_source_matches(source, &existing)? {
+            all_matching_versions_equivalent = false;
+        }
+    }
+    if matching_count == 0 || (matching_count == 1 && all_matching_versions_equivalent) {
+        return Ok(());
+    }
+
+    Err(StorageError::DataMovementOverwriteErr(
+        bucket.to_owned(),
+        object.to_owned(),
+        source_version_id.map(|version_id| version_id.to_string()).unwrap_or_default(),
+    )
+    .into())
+}
+
 impl SetDisks {
     pub(super) async fn require_current_restore_operation_id(
         &self,
@@ -4698,6 +4736,9 @@ impl SetDisks {
             });
         }
 
+        self.validate_decommission_tier_free_version_target(bucket, object, fi)
+            .await?;
+
         let disks = self.disks.read().await.clone();
         let write_quorum = self.default_write_quorum();
         let futures = disks.into_iter().map(|disk| {
@@ -4722,6 +4763,26 @@ impl SetDisks {
         resolve_tiered_decommission_write_quorum_result(&errs, write_quorum, bucket, object)
     }
 
+    pub(crate) async fn validate_decommission_tier_free_version_target(
+        &self,
+        bucket: &str,
+        object: &str,
+        fi: &FileInfo,
+    ) -> Result<()> {
+        // The caller holds the source and target object locks. Inspect every
+        // target disk before an idempotent return or metadata fan-out so a
+        // sub-quorum conflict cannot be hidden by a successful quorum.
+        let disks = self.disks.read().await.clone();
+        let preflight = disks
+            .iter()
+            .flatten()
+            .map(|disk| check_decommission_tier_free_version_target(disk, bucket, object, fi));
+        for result in join_all(preflight).await {
+            result?;
+        }
+        Ok(())
+    }
+
     #[tracing::instrument(skip(self, fi, opts))]
     pub(crate) async fn decommission_tiered_object(
         &self,
diff --git a/crates/ecstore/src/store/init.rs b/crates/ecstore/src/store/init.rs
index 451e42242..98eab2c52 100644
--- a/crates/ecstore/src/store/init.rs
+++ b/crates/ecstore/src/store/init.rs
@@ -595,7 +595,7 @@ mod tests {
     use crate::{
         bucket::replication::{ReplicationState, ReplicationStatusType, replication_statuses_map},
         core::pools::{POOL_META_VERSION, PoolDecommissionInfo, PoolMeta, PoolStatus},
-        disk::endpoint::Endpoint,
+        disk::{DiskAPI, endpoint::Endpoint},
         error::{Error, Result, StorageError},
         io_support::rio::{WritePlan, compression_metadata_value},
         layout::endpoints::{EndpointServerPools, Endpoints, PoolEndpoints},
@@ -1307,6 +1307,77 @@ mod tests {
         });
     }
 
+    #[cfg(feature = "test-util")]
+    async fn seed_transitioned_free_version(
+        ctx: &Arc<crate::runtime::instance::InstanceContext>,
+        store: &Arc<crate::store::ECStore>,
+        bucket: &str,
+        object: &str,
+    ) -> (uuid::Uuid, uuid::Uuid) {
+        let tier_name = format!("DECOMFREE{}", uuid::Uuid::new_v4().simple());
+        register_mock_tier(&ctx.tier_config_mgr(), &tier_name).await;
+
+        let mut reader = PutObjReader::from_vec(b"transitioned source bytes".to_vec());
+        let source = store.pools[0]
+            .put_object(
+                bucket,
+                object,
+                &mut reader,
+                &ObjectOptions {
+                    versioned: true,
+                    ..Default::default()
+                },
+            )
+            .await
+            .expect("write transitioned decommission source");
+        let source_version = source.version_id.expect("transitioned source must be versioned");
+        store.pools[0]
+            .transition_object(
+                bucket,
+                object,
+                &ObjectOptions {
+                    versioned: true,
+                    version_id: Some(source_version.to_string()),
+                    transition: TransitionOptions {
+                        status: TRANSITION_PENDING.to_string(),
+                        tier: tier_name,
+                        etag: source.etag.clone().expect("transitioned source must have an ETag"),
+                        ..Default::default()
+                    },
+                    mod_time: source.mod_time,
+                    ..Default::default()
+                },
+            )
+            .await
+            .expect("transition source before decommission");
+        store.pools[0]
+            .delete_object(
+                bucket,
+                object,
+                ObjectOptions {
+                    versioned: true,
+                    version_id: Some(source_version.to_string()),
+                    ..Default::default()
+                },
+            )
+            .await
+            .expect("delete transitioned source version");
+
+        let versions = store.pools[0]
+            .get_disks_by_key(object)
+            .load_file_info_versions_exact(bucket, object)
+            .await
+            .expect("source versions should decode after transition delete")
+            .expect("source free version should remain after transition delete");
+        let free_version = versions
+            .versions
+            .iter()
+            .find(|version| version.tier_free_version())
+            .and_then(|version| version.version_id)
+            .expect("transition delete should create a free version");
+        (source_version, free_version)
+    }
+
     async fn write_decommission_test_multipart_source(
         store: &Arc<crate::store::ECStore>,
         pool_idx: usize,
@@ -3846,6 +3917,268 @@ mod tests {
         shutdown.cancel();
     }
 
+    #[cfg(feature = "test-util")]
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    #[serial_test::serial(storage_class_env)]
+    async fn decommission_entry_skips_cleanup_only_marker_when_free_version_is_present() {
+        let temp_dir = tempfile::tempdir().expect("create free-version decommission store dir");
+        let (ctx, store, shutdown) =
+            without_storage_class_env(build_isolated_test_store(temp_dir.path(), "decommission-free-marker", &[4, 4])).await;
+        crate::bucket::metadata_sys::init_bucket_metadata_sys(store.clone(), Vec::new()).await;
+        let bucket = format!("decom-free-marker-{}", uuid::Uuid::new_v4());
+        let object = "free-marker-object";
+        store
+            .make_bucket(&bucket, &MakeBucketOptions::default())
+            .await
+            .expect("create free-version decommission bucket");
+        let (_, free_version) = seed_transitioned_free_version(&ctx, &store, &bucket, object).await;
+        let mut target_reader = PutObjReader::from_vec(b"target ordinary bytes".to_vec());
+        let target_w = store.pools[1]
+            .put_object(
+                &bucket,
+                object,
+                &mut target_reader,
+                &ObjectOptions {
+                    versioned: true,
+                    ..Default::default()
+                },
+            )
+            .await
+            .expect("write unrelated target version");
+        let target_w_version = target_w.version_id.expect("target version should have an id");
+        let marker = store.pools[0]
+            .delete_object(
+                &bucket,
+                object,
+                ObjectOptions {
+                    versioned: true,
+                    ..Default::default()
+                },
+            )
+            .await
+            .expect("write cleanup-only delete marker");
+        assert!(marker.delete_marker);
+
+        mark_test_pool_decommissioning(&store, 0).await;
+        let source_set = store.pools[0].get_disks_by_key(object);
+        store
+            .decommission_entry_for_test_with_bucket_incarnation(
+                0,
+                MetaCacheEntry {
+                    name: object.to_string(),
+                    ..Default::default()
+                },
+                bucket.clone(),
+                source_set.clone(),
+            )
+            .await
+            .expect("real decommission entry should migrate the free version");
+
+        let target_versions = store.pools[1]
+            .get_disks_by_key(object)
+            .load_file_info_versions_exact(&bucket, object)
+            .await
+            .expect("target versions should decode")
+            .expect("target free version should be present");
+        assert!(
+            target_versions
+                .versions
+                .iter()
+                .any(|version| { version.version_id == Some(free_version) && version.tier_free_version() })
+        );
+        let retained_w = target_versions
+            .versions
+            .iter()
+            .find(|version| version.version_id == Some(target_w_version))
+            .expect("unrelated target version should remain");
+        assert!(!retained_w.deleted && !retained_w.tier_free_version());
+        assert_eq!(retained_w.size, target_w.size);
+        assert_eq!(retained_w.get_etag(), target_w.etag);
+        assert!(
+            target_versions
+                .versions
+                .iter()
+                .all(|version| { version.tier_free_version() || !version.deleted })
+        );
+        assert!(
+            source_set
+                .load_file_info_versions_exact(&bucket, object)
+                .await
+                .expect("source versions should be readable after cleanup")
+                .is_none(),
+            "successful free-version migration should permit source cleanup"
+        );
+        shutdown.cancel();
+    }
+
+    #[cfg(feature = "test-util")]
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    #[serial_test::serial(storage_class_env)]
+    async fn decommission_entry_rejects_subquorum_free_version_conflict_and_retains_source() {
+        let temp_dir = tempfile::tempdir().expect("create sub-quorum free-version store dir");
+        let (ctx, store, shutdown) =
+            without_storage_class_env(build_isolated_test_store(temp_dir.path(), "decommission-free-conflict", &[4, 4])).await;
+        crate::bucket::metadata_sys::init_bucket_metadata_sys(store.clone(), Vec::new()).await;
+        let bucket = format!("decom-free-conflict-{}", uuid::Uuid::new_v4());
+        let object = "free-conflict-object";
+        store
+            .make_bucket(&bucket, &MakeBucketOptions::default())
+            .await
+            .expect("create sub-quorum conflict bucket");
+        let (_, free_version) = seed_transitioned_free_version(&ctx, &store, &bucket, object).await;
+        let source_free = store.pools[0]
+            .get_disks_by_key(object)
+            .load_file_info_versions_exact(&bucket, object)
+            .await
+            .expect("source free version should decode before crash replay setup")
+            .and_then(|versions| {
+                versions
+                    .versions
+                    .into_iter()
+                    .find(|version| version.version_id == Some(free_version))
+            })
+            .expect("source free version should be available for crash replay setup");
+
+        let mut target_reader = PutObjReader::from_vec(b"target ordinary bytes".to_vec());
+        let target = store.pools[1]
+            .put_object(
+                &bucket,
+                object,
+                &mut target_reader,
+                &ObjectOptions {
+                    versioned: true,
+                    ..Default::default()
+                },
+            )
+            .await
+            .expect("seed ordinary target version");
+        let target_version = target.version_id.expect("target version must have an ID");
+        let target_disks = store.pools[1].get_disks_by_key(object).disks.read().await.clone();
+        for disk in target_disks.iter().skip(1) {
+            disk.as_ref()
+                .expect("target crash replay quorum disk should be online")
+                .write_metadata("", &bucket, object, source_free.clone())
+                .await
+                .expect("seed an equivalent free version on the target quorum");
+        }
+        let conflict_path = temp_dir
+            .path()
+            .join(format!("pool1/set0/disk0/{bucket}/{object}/{STORAGE_FORMAT_FILE}"));
+        let encoded = tokio::fs::read(&conflict_path)
+            .await
+            .expect("target metadata should be readable");
+        let mut metadata = FileMeta::load(&encoded).expect("target metadata should decode");
+        let target_index = metadata
+            .versions
+            .iter()
+            .position(|version| version.header.version_id == Some(target_version))
+            .expect("target version should be present on the conflict disk");
+        let mut target_meta = metadata.versions[target_index]
+            .parse_version_meta()
+            .expect("target version metadata should decode");
+        target_meta
+            .object
+            .as_mut()
+            .expect("target conflict must remain an ordinary object")
+            .version_id = Some(free_version);
+        metadata.versions[target_index] = target_meta.try_into().expect("conflict metadata should encode");
+        let expected_conflict_meta = metadata.versions[target_index].meta.clone();
+        let expected_conflict = metadata.versions[target_index]
+            .into_fileinfo(&bucket, object, true)
+            .expect("conflict metadata should decode as an ordinary object");
+        let duplicate_free: rustfs_filemeta::FileMetaShallowVersion = rustfs_filemeta::FileMetaVersion::from(source_free.clone())
+            .try_into()
+            .expect("duplicate free metadata should encode");
+        metadata.versions.insert(target_index, duplicate_free);
+        tokio::fs::write(&conflict_path, metadata.marshal_msg().expect("conflict metadata should encode"))
+            .await
+            .expect("write sub-quorum conflict metadata");
+
+        mark_test_pool_decommissioning(&store, 0).await;
+        let source_set = store.pools[0].get_disks_by_key(object);
+        store
+            .decommission_entry_for_test_with_bucket_incarnation(
+                0,
+                MetaCacheEntry {
+                    name: object.to_string(),
+                    ..Default::default()
+                },
+                bucket.clone(),
+                source_set.clone(),
+            )
+            .await
+            .expect("conflicted decommission entry should retain the source and retry later");
+
+        let source_versions = source_set
+            .load_file_info_versions_exact(&bucket, object)
+            .await
+            .expect("retained source versions should decode")
+            .expect("source free version should be retained after conflict");
+        assert!(
+            source_versions
+                .versions
+                .iter()
+                .any(|version| { version.version_id == Some(free_version) && version.tier_free_version() })
+        );
+        let post_encoded = tokio::fs::read(&conflict_path)
+            .await
+            .expect("conflict metadata should remain readable");
+        let post_metadata = FileMeta::load(&post_encoded).expect("post-conflict metadata should decode");
+        let same_id = post_metadata
+            .versions
+            .iter()
+            .filter(|version| version.header.version_id == Some(free_version))
+            .collect::<Vec<_>>();
+        assert_eq!(same_id.len(), 2, "conflict metadata should retain both same-ID records");
+        assert_eq!(same_id.iter().filter(|version| version.free_version()).count(), 1);
+        assert_eq!(same_id.iter().filter(|version| !version.free_version()).count(), 1);
+        let post_conflict = same_id
+            .into_iter()
+            .find(|version| !version.free_version())
+            .expect("ordinary conflict version must remain addressable by the source ID");
+        let post_conflict_info = post_conflict
+            .into_fileinfo(&bucket, object, true)
+            .expect("post-conflict ordinary metadata should decode");
+        assert!(!post_conflict_info.deleted && !post_conflict_info.tier_free_version());
+        assert_eq!(post_conflict.meta, expected_conflict_meta);
+        assert_eq!(post_conflict_info.size, expected_conflict.size);
+        assert_eq!(post_conflict_info.data_dir, expected_conflict.data_dir);
+        assert_eq!(post_conflict_info.metadata, expected_conflict.metadata);
+        assert_eq!(post_conflict_info.get_etag(), expected_conflict.get_etag());
+
+        for disk_index in 0..4 {
+            let target_path = temp_dir
+                .path()
+                .join(format!("pool1/set0/disk{disk_index}/{bucket}/{object}/{STORAGE_FORMAT_FILE}"));
+            let target_encoded = tokio::fs::read(&target_path)
+                .await
+                .expect("target metadata should remain readable");
+            let target_meta = FileMeta::load(&target_encoded).expect("target metadata should decode");
+            let same_id = target_meta
+                .versions
+                .iter()
+                .filter(|version| version.header.version_id == Some(free_version))
+                .collect::<Vec<_>>();
+            if disk_index == 0 {
+                assert_eq!(same_id.len(), 2);
+                assert!(same_id[0].free_version());
+                assert!(!same_id[1].free_version());
+            } else {
+                assert_eq!(same_id.len(), 1);
+                assert!(same_id[0].free_version());
+            }
+        }
+        let sweep_err = store
+            .check_after_decommission_for_test(0)
+            .await
+            .expect_err("final sweep must report the retained free version");
+        assert!(
+            sweep_err.to_string().contains("version(s) were found"),
+            "unexpected final sweep error: {sweep_err}"
+        );
+        shutdown.cancel();
+    }
+
     #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
     #[serial_test::serial(storage_class_env)]
     async fn versioned_batch_delete_marker_skips_decommission_source() {
diff --git a/crates/ecstore/src/store/object.rs b/crates/ecstore/src/store/object.rs
index 566576034..8f30269d2 100644
--- a/crates/ecstore/src/store/object.rs
+++ b/crates/ecstore/src/store/object.rs
@@ -1494,13 +1494,15 @@ fn is_equivalent_data_movement_tiered_object(source: &rustfs_filemeta::FileInfo,
         && source_actual_size == target_actual_size
 }
 
-fn tiered_data_movement_source_matches(
+pub(crate) fn tiered_data_movement_source_matches(
     expected: &rustfs_filemeta::FileInfo,
     current: &rustfs_filemeta::FileInfo,
 ) -> Result<bool> {
     let expected_backend = crate::services::tier::tier::tier_destination_id_from_metadata(&expected.metadata)?;
     let current_backend = crate::services::tier::tier::tier_destination_id_from_metadata(&current.metadata)?;
     Ok(expected.version_id == current.version_id
+        && expected.deleted == current.deleted
+        && expected.tier_free_version() == current.tier_free_version()
         && expected.data_dir == current.data_dir
         && expected.mod_time == current.mod_time
         && expected.size == current.size
@@ -2363,6 +2365,10 @@ impl ECStore {
                 return Err(Error::DiskFull);
             }
             let equivalent = if is_free_version {
+                self.pools[target_pool_idx]
+                    .get_disks_by_key(&object)
+                    .validate_decommission_tier_free_version_target(bucket, &object, &fi)
+                    .await?;
                 self.has_equivalent_data_movement_tier_free_version(bucket, &object, &fi, target_pool_idx)
                     .await?
             } else {
@@ -2377,6 +2383,10 @@ impl ECStore {
         }
 
         let result = if is_free_version {
+            self.pools[idx]
+                .get_disks_by_key(&object)
+                .validate_decommission_tier_free_version_target(bucket, &object, &fi)
+                .await?;
             if self
                 .has_equivalent_data_movement_tier_free_version(bucket, &object, &fi, idx)
                 .await?
diff --git a/crates/filemeta/src/filemeta.rs b/crates/filemeta/src/filemeta.rs
index 9225a1edb..7e7f61f6d 100644
--- a/crates/filemeta/src/filemeta.rs
+++ b/crates/filemeta/src/filemeta.rs
@@ -462,6 +462,10 @@ impl FileMeta {
         };
 
         if let Some(fidx) = existing_idx {
+            let existing = self.versions[fidx].parse_version_meta()?;
+            if existing.free_version() != version.free_version() {
+                return Err(Error::other("cannot replace a free version with a non-free version"));
+            }
             return self.set_idx(fidx, version);
         }