diff --git a/rust/lance/src/dataset/tests/dataset_merge_update.rs b/rust/lance/src/dataset/tests/dataset_merge_update.rs
index 7fa03d6e78d..c6f448040c2 100644
--- a/rust/lance/src/dataset/tests/dataset_merge_update.rs
+++ b/rust/lance/src/dataset/tests/dataset_merge_update.rs
@@ -1047,7 +1047,8 @@ async fn test_datafile_replacement_error() {
         Operation::DataReplacement {
             replacements: vec![DataReplacementGroup(0, new_data_file)],
         },
-        Some(2),
+        // read at the current version (after the Merge above)
+        Some(dataset.manifest.version),
         None,
         None,
         Arc::new(Default::default()),
diff --git a/rust/lance/src/io/commit/conflict_resolver.rs b/rust/lance/src/io/commit/conflict_resolver.rs
index b242cd5b3dd..dc898534c89 100644
--- a/rust/lance/src/io/commit/conflict_resolver.rs
+++ b/rust/lance/src/io/commit/conflict_resolver.rs
@@ -904,13 +904,42 @@ impl<'a> TransactionRebase<'a> {
             match &other_transaction.operation {
                 Operation::Append { .. }
                 | Operation::Clone { .. }
-                | Operation::Delete { .. }
-                | Operation::Update { .. }
-                | Operation::Merge { .. }
                 | Operation::UpdateConfig { .. }
                 | Operation::ReserveFragments { .. }
                 | Operation::Project { .. }
                 | Operation::UpdateBases { .. } => Ok(()),
+                Operation::Merge { .. } => {
+                    // Merge rewrites the whole fragment list; always conflict
+                    // (symmetric with check_merge_txn).
+                    Err(self.retryable_conflict_err(other_transaction, other_version))
+                }
+                Operation::Update {
+                    updated_fragments,
+                    removed_fragment_ids,
+                    ..
+                }
+                | Operation::Delete {
+                    updated_fragments,
+                    deleted_fragment_ids: removed_fragment_ids,
+                    ..
+                } => {
+                    // A concurrent Update/Delete that changed one of our target
+                    // fragments makes our positional column file stale; conflict so
+                    // the committer rebuilds (lance otherwise accepts it silently).
+                    for replacement in replacements {
+                        let touches_our_fragment = updated_fragments
+                            .iter()
+                            .map(|f| f.id)
+                            .chain(removed_fragment_ids.iter().copied())
+                            .any(|id| id == replacement.0);
+                        if touches_our_fragment {
+                            return Err(
+                                self.retryable_conflict_err(other_transaction, other_version)
+                            );
+                        }
+                    }
+                    Ok(())
+                }
                 Operation::CreateIndex { new_indices, .. } => {
                     // A data replacement only conflicts if it is updating the field that
                     // is being indexed.
@@ -3258,7 +3287,7 @@ mod tests {
             (
                 "DataReplacement vs Rewrite on different fragment",
                 Operation::DataReplacement {
-                    replacements: vec![DataReplacementGroup(0, data_file_frag0_fields01)],
+                    replacements: vec![DataReplacementGroup(0, data_file_frag0_fields01.clone())],
                 },
                 Operation::Rewrite {
                     groups: vec![RewriteGroup {
@@ -3270,6 +3299,80 @@ mod tests {
                 },
                 Compatible,
             ),
+            // A concurrent Update/Delete on a fragment we replace a column in must
+            // conflict, else the stale positional file is applied silently.
+            (
+                "DataReplacement vs Update on same fragment",
+                Operation::DataReplacement {
+                    replacements: vec![DataReplacementGroup(0, data_file_frag0_fields01.clone())],
+                },
+                Operation::Update {
+                    updated_fragments: vec![Fragment::new(0)],
+                    removed_fragment_ids: vec![],
+                    new_fragments: vec![],
+                    fields_modified: vec![],
+                    merged_generations: Vec::new(),
+                    fields_for_preserving_frag_bitmap: vec![],
+                    update_mode: None,
+                    inserted_rows_filter: None,
+                    updated_fragment_offsets: None,
+                },
+                Retryable,
+            ),
+            (
+                "DataReplacement vs Update on different fragment",
+                Operation::DataReplacement {
+                    replacements: vec![DataReplacementGroup(0, data_file_frag0_fields01.clone())],
+                },
+                Operation::Update {
+                    updated_fragments: vec![Fragment::new(1)],
+                    removed_fragment_ids: vec![],
+                    new_fragments: vec![],
+                    fields_modified: vec![],
+                    merged_generations: Vec::new(),
+                    fields_for_preserving_frag_bitmap: vec![],
+                    update_mode: None,
+                    inserted_rows_filter: None,
+                    updated_fragment_offsets: None,
+                },
+                Compatible,
+            ),
+            (
+                "DataReplacement vs Delete on same fragment",
+                Operation::DataReplacement {
+                    replacements: vec![DataReplacementGroup(0, data_file_frag0_fields01.clone())],
+                },
+                Operation::Delete {
+                    deleted_fragment_ids: vec![],
+                    updated_fragments: vec![Fragment::new(0)],
+                    predicate: "a > 0".to_string(),
+                },
+                Retryable,
+            ),
+            (
+                "DataReplacement vs Delete that removes the fragment",
+                Operation::DataReplacement {
+                    replacements: vec![DataReplacementGroup(0, data_file_frag0_fields01.clone())],
+                },
+                Operation::Delete {
+                    deleted_fragment_ids: vec![0],
+                    updated_fragments: vec![],
+                    predicate: "a > 0".to_string(),
+                },
+                Retryable,
+            ),
+            // Merge rewrites the whole fragment list -> always conflicts.
+            (
+                "DataReplacement vs Merge",
+                Operation::DataReplacement {
+                    replacements: vec![DataReplacementGroup(0, data_file_frag0_fields01)],
+                },
+                Operation::Merge {
+                    fragments: vec![Fragment::new(0)],
+                    schema: lance_core::datatypes::Schema::default(),
+                },
+                Retryable,
+            ),
         ];
 
         for (description, op1, op2, expected) in cases {