diff --git a/include/common_helper.h b/include/common_helper.h
index dabae98..62f6952 100644
--- a/include/common_helper.h
+++ b/include/common_helper.h
@@ -30,7 +30,6 @@ find_border(base_node* const root, const key_slice_type key_slice,
             const key_length_type key_slice_length, status& special_status) {
     special_status = status::OK;
 retry:
-#ifndef NDEBUG
     if (root == nullptr) {
         LOG(ERROR) << log_location_prefix << "find_border: root: " << root
                    << ", key_slice: " << key_slice
@@ -39,7 +38,6 @@ find_border(base_node* const root, const key_slice_type key_slice,
         // if special status is ok, it is just after called.
         // if special status is warn, it is just after retry one.
     }
-#endif
 
     base_node* n = root;
     node_version64_body v = n->get_stable_version();
@@ -49,14 +47,13 @@ find_border(base_node* const root, const key_slice_type key_slice,
     }
     if (v.get_deleted()) {
         // root && deleted node.
-#ifndef NDEBUG
         if (n == nullptr) {
             LOG(ERROR) << log_location_prefix << "find_border: root: " << root
                        << ", key_slice: " << key_slice
                        << ", key_slice_length: " << key_slice_length
-                       << ", special_status: " << special_status;
+                       << ", special_status: " << special_status
+                       << ", version: " << v;
         }
-#endif
         return std::make_tuple(dynamic_cast<border_node*>(n), v);
     }
     /**
@@ -79,14 +76,12 @@ find_border(base_node* const root, const key_slice_type key_slice,
         }
         n = n_child;
     }
-#ifndef NDEBUG
     if (n == nullptr) {
         LOG(ERROR) << log_location_prefix << "find_border: root: " << root
                    << ", key_slice: " << key_slice
                    << ", key_slice_length: " << key_slice_length
                    << ", special_status: " << special_status;
     }
-#endif
     return std::make_tuple(dynamic_cast<border_node*>(n), v);
 }
 
diff --git a/include/interface_remove.h b/include/interface_remove.h
index 233c3e3..996bece 100644
--- a/include/interface_remove.h
+++ b/include/interface_remove.h
@@ -65,14 +65,17 @@ namespace yakushima {
     constexpr std::size_t tuple_node_index = 0;
     constexpr std::size_t tuple_v_index = 1;
     border_node* target_border = std::get<tuple_node_index>(node_and_v);
-#ifndef NDEBUG
+    node_version64_body v_at_fb = std::get<tuple_v_index>(node_and_v);
+
     // check target_border is not nullptr
     if (target_border == nullptr) {
-        LOG(ERROR) << log_location_prefix << "root: " << root
-                   << ", key_slice: " << key_slice
-                   << ", key_length: " << key_length
-                   << ", special_status: " << special_status;
-        return status::ERR_FATAL;
+        // TODO
+        /**
+         * This code path is not expected to be reached. However, sometimes 
+         * this code path is reached. You may need to make appropriate use of 
+         * compiler fences.
+        */
+        goto retry_from_root;
     }
     // check target_border is border node.
     if (typeid(*target_border) != typeid(border_node)) {
@@ -80,8 +83,7 @@ namespace yakushima {
                    << "find_border return not border node.";
         return status::ERR_FATAL;
     }
-#endif
-    node_version64_body v_at_fb = std::get<tuple_v_index>(node_and_v);
+
 retry_fetch_lv:
     node_version64_body v_at_fetch_lv{};
     std::size_t lv_pos = 0;