Quartz Failure On Job Recovery

I'm new to JSP and Quartz Scheduling! In this project, I'm trying to make the quartz scheduler continue functioning in case the server is turned off then on ignoring the missed jobs.

For this, I researched JobPersistence and I have modified the quartz.properties file as the following:

org.quartz.threadPool.threadCount=5
org.quartz.jobStore.class = org.quartz.impl.jdbcjobstore.JobStoreTX
org.quartz.jobStore.tablePrefix = QRTZ_
org.quartz.jobStore.useProperties = true
org.quartz.jobStore.driverDelegateClass = org.quartz.impl.jdbcjobstore.StdJDBCDelegate
org.quartz.jobStore.dataSource = myDB
org.quartz.dataSource.myDB.driver = com.mysql.jdbc.Driver
org.quartz.dataSource.myDB.URL = jdbc:mysql://localhost:3306/contacts
org.quartz.dataSource.myDB.user = root
org.quartz.dataSource.myDB.password = root

the web.xml file contains the following:

...
<listener>
  <listener-class>
     org.quartz.ee.servlet.QuartzInitializerListener
  </listener-class>
</listener>
...

I've added the tables to the DB and when I select I can see that it really inserted triggers to its tables.

The trigger is built as the following:

Trigger trig = TriggerBuilder
.newTrigger()
.startAt(scal.getTime())
.withSchedule(
    SimpleScheduleBuilder.simpleSchedule()
    .withIntervalInMinutes(minutes).repeatForever())
    .endAt(ecal.getTime()).build();

Now, when I run my web app, I schedule a job and it executes. Then, I turn off the tomcat server and start it again. It prints the following error to the logger:

org.quartz.SchedulerConfigException: Failure occured during job recovery. [See nested exception: org.quartz.JobPersistenceException: Couldn't recover jobs: null [See nested exception: java.lang.NullPointerException]]

I have tried executing the following statement once in MySQLWorkbench:

UPDATE QRTZ_TRIGGERS SET NEXT_FIRE_TIME=1 WHERE NEXT_FIRE_TIME < 0;

Now, I got this new error:

.manage - MisfireHandler: Error handling misfires: Unexpected runtime exception: null

org.quartz.JobPersistenceException: Unexpected runtime exception: null [See nested exception: java.lang.NullPointerException]

If you want me to edit and include the stackTrace, I can do that...