Error flushing statements - Signal Event

Hi Dear Camunders,

I am using Camunda 7.12.2 with Postgre 10.7
with server.xml set up as following

<Resource name="jdbc/ProcessEngine" auth="Container" type="javax.sql.DataSource" factory="org.apache.tomcat.jdbc.pool.DataSourceFactory" uniqueResourceName="process-engine" driverClassName="org.postgresql.Driver" url="jdbc:postgresql://xxxxx/camunda" defaultTransactionIsolation="READ_COMMITTED" username="xx" password="xx" maxActive="20" minIdle="5" maxIdle="20" testOnBorrow="true" validationQuery="SELECT 1" validationInterval="36000"/>

The following is process model excerpt

While executing I often get the similar stacktrace
stacktrace.txt (11.8 KB)

I am not sure whether it is thanks to poor design (my plan so far is to remove the signal event) or is it a bug?

Best regards