diff --git a/casadm/extended_err_msg.c b/casadm/extended_err_msg.c
index e529d14..a7e6a7d 100644
--- a/casadm/extended_err_msg.c
+++ b/casadm/extended_err_msg.c
@@ -61,6 +61,10 @@ struct {
 		OCF_ERR_TOO_MANY_CORES,
 		"Too many core devices in cache"
 	},
+	{
+		OCF_ERR_CORE_EXIST,
+		"Core id already used"
+	},
 	{
 		OCF_ERR_CORE_NOT_AVAIL,
 		"Core device not available"
diff --git a/modules/cas_cache/layer_cache_management.c b/modules/cas_cache/layer_cache_management.c
index 78232f9..d1e7872 100644
--- a/modules/cas_cache/layer_cache_management.c
+++ b/modules/cas_cache/layer_cache_management.c
@@ -534,8 +534,7 @@ int cache_mngt_prepare_core_cfg(struct ocf_mngt_core_config *cfg,
 		struct kcas_insert_core *cmd_info)
 {
 	struct block_device *bdev;
-	static char core_name[OCF_CORE_NAME_SIZE];
-	struct cache_priv *cache_priv;
+	char core_name[OCF_CORE_NAME_SIZE] = {};
 	ocf_cache_t cache;
 	uint16_t core_id;
 	int result;
@@ -546,17 +545,19 @@ int cache_mngt_prepare_core_cfg(struct ocf_mngt_core_config *cfg,
 	if (cmd_info->core_id == OCF_CORE_MAX) {
 		result = mngt_get_cache_by_id(cas_ctx, cmd_info->cache_id,
 				&cache);
-		if (result)
+		if (result && result != -OCF_ERR_CACHE_NOT_EXIST) {
 			return result;
+		} else if (!result) {
+			struct cache_priv *cache_priv;
+			cache_priv = ocf_cache_get_priv(cache);
+			ocf_mngt_cache_put(cache);
 
-		cache_priv = ocf_cache_get_priv(cache);
-		ocf_mngt_cache_put(cache);
+			core_id = find_free_core_id(cache_priv->core_id_bitmap);
+			if (core_id == OCF_CORE_MAX)
+				return -OCF_ERR_INVAL;
 
-		core_id = find_free_core_id(cache_priv->core_id_bitmap);
-		if (core_id == OCF_CORE_MAX)
-			return -OCF_ERR_INVAL;
-
-		cmd_info->core_id = core_id;
+			cmd_info->core_id = core_id;
+		}
 	}
 
 	snprintf(core_name, sizeof(core_name), "core%d", cmd_info->core_id);