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"