Dette er et sent svar, men jeg havde det samme problem. Det skyldes forkert konfiguration af c3po.
Brug venligst nedenstående c3po-konfiguration:
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
<property name="driverClass" value="${jdbc.driverClassName}" />
<property name="jdbcUrl" value="${jdbc.url}" />
<property name="user" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
<property name="checkoutTimeout" value="30000" />
<property name="idleConnectionTestPeriod" value="30"/>
<property name="initialPoolSize" value="10" />
<property name="maxIdleTime" value="30" />
<property name="maxPoolSize" value="100" />
<property name="minPoolSize" value="10" />
<property name="maxStatements" value="10" />
</bean