In some cases using an Oracle database an ORA-08177 "Can't serialize access for this transaction" error can appear while using the application. This can be fixed by setting an auto Session Trigger that is executed after the application connects to the database.
CREATE OR REPLACE TRIGGER amana
BEGIN
EXECUTE IMMEDIATE 'ALTER SESSION SET ISOLATION_LEVEL READ COMMITTED';
END;
For more information please refer to the official Oracle documentation:
https://docs.oracle.com/javadb/10.6.2.1/ref/rrefsqlj41180.html