DomainStoppedException: Domain project was shutdown...

Hello everyone.

I have a bootique application which uses a 5 minute cron job to update DB
via some rules.
I've noticed that sometimes it throws DomainStoppedException.
It is hard to reproduce it as it happens just a few times per day.

I can't get why this might happen. Any thoughts?

org.apache.cayenne.access.DomainStoppedException: [v.4.0 Aug 06 2018
> 12:11:43] Domain project was shutdown and can no longer be used to access
> the database
>         at
> org.apache.cayenne.access.DataDomain.checkStopped(DataDomain.java:181)
> ~[cayenne-server-4.0.jar:4.0]
>         at
> org.apache.cayenne.access.DataDomain.onQuery(DataDomain.java:554)
> ~[cayenne-server-4.0.jar:4.0]
>         at
> org.apache.cayenne.util.ObjectContextQueryAction.runQuery(ObjectContextQueryAction.java:406)
> ~[cayenne-server-4.0.jar:4.0]
>         at
> org.apache.cayenne.util.ObjectContextQueryAction.executePostCache(ObjectContextQueryAction.java:107)
> ~[cayenne-server-4.0.jar:4.0]
>         at
> org.apache.cayenne.util.ObjectContextQueryAction.execute(ObjectContextQueryAction.java:94)
> ~[cayenne-server-4.0.jar:4.0]
>         at
> org.apache.cayenne.access.DataContext.onQuery(DataContext.java:965)
> ~[cayenne-server-4.0.jar:4.0]
>         at
> org.apache.cayenne.access.DataContext.performQuery(DataContext.java:954)
> ~[cayenne-server-4.0.jar:4.0]
>         at
> org.apache.cayenne.access.ToOneFault.doResolveFault(ToOneFault.java:81)
> ~[cayenne-server-4.0.jar:4.0]
>         at
> org.apache.cayenne.access.ToOneFault.resolveFault(ToOneFault.java:54)
> ~[cayenne-server-4.0.jar:4.0]
>         at
> org.apache.cayenne.CayenneDataObject.readProperty(CayenneDataObject.java:180)
> ~[cayenne-server-4.0.jar:4.0]
>         at
> org.apache.cayenne.CayenneDataObject.setToOneTarget(CayenneDataObject.java:357)
> ~[cayenne-server-4.0.jar:4.0]
>