RS delete form messages with MySQL

6:25:46,566 ERROR OLATRuntimeException:175 - OLAT::ERROR ^%^ N1-E9 ^%^ org.olat.core.logging
https://xyz.de/auth/RepositoryEntry/320077827/CourseNode/79648595970448/Message/2576318464 ^%^ Mozilla/5.0 (Windows NT 6.1; WOW64; rv:55.0) Gecko/20100101 Firefox/55.0

**RedScreen** org.hibernate.exception.ConstraintViolationException: could not execute statement

<dispatchinfo>
	<componentinfo>
		<compname>link_0</compname>
		<compclass>org.olat.core.gui.components.link.Link</compclass>
		<extendedinfo>n/a</extendedinfo>
		<event>
			<class&gt;org.olat.core.gui.control.Event</class&gt;
			<command>link_0</command>
			<tostring>com:link_0,org.olat.core.gui.control.Event@be46a54a</tostring>
		</event>
	</componentinfo>
	<controllerinfo>
		<controllername>org.olat.core.gui.control.generic.modal.DialogBoxController</controllername>
		<controllername>org.olat.modules.fo.ui.MessageListController</controllername>
		<controllername>org.olat.modules.fo.ui.ForumController</controllername>
		<controllername>org.olat.course.nodes.fo.FOCourseNodeRunController</controllername>
		<controllername>org.olat.course.run.RunMainController</controllername>
		<controllername>org.olat.course.run.CourseRuntimeController</controllername>
		<controllername>org.olat.core.commons.fullWebApp.BaseFullWebappController</controllername>
	</controllerinfo>
</dispatchinfo>

>>> stack of 1.cause::org.olat.core.logging.OLATRuntimeException: org.hibernate.exception.ConstraintViolationException: could not execute statement
-> at org.olat.core.gui.exception.ExceptionWindowController.<init>(ExceptionWindowController.java:116)
   at org.olat.core.gui.exception.MsgFactory.createMessageChiefController(MsgFactory.java:57)
   at org.olat.core.gui.exception.MsgFactory.createMessageChiefController(MsgFactory.java:46)
   at org.olat.core.gui.components.Window.dispatchRequest(Window.java:549)
   at org.olat.core.gui.components.Window.doDispatchRequest(Window.java:242)
   at org.olat.core.gui.components.AbstractComponent.dispatchRequest(AbstractComponent.java:193)
   at org.olat.dispatcher.AuthenticatedDispatcher.processValidDispatchURI(AuthenticatedDispatcher.java:273)
   at org.olat.dispatcher.AuthenticatedDispatcher.execute(AuthenticatedDispatcher.java:190)
   at org.olat.core.servlets.OpenOLATServlet.executeUserRequest(OpenOLATServlet.java:292)
   at org.olat.core.servlets.OpenOLATServlet.doPost(OpenOLATServlet.java:235)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:644)
>>> stack of 2.cause::javax.persistence.PersistenceException: org.hibernate.exception.ConstraintViolationException: could not execute statement
-> at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:147)
   at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:155)
   at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1419)
   at org.hibernate.Query.getResultList(Query.java:427) at org.olat.modules.fo.manager.ForumManager.getForumThreads(ForumManager.java:325)
   at org.olat.modules.fo.ui.ThreadListController.loadModel(ThreadListController.java:163)
   at org.olat.modules.fo.ui.ForumController.doThreadList(ForumController.java:353)
   at org.olat.modules.fo.ui.ForumController.event(ForumController.java:215)
   at org.olat.core.gui.control.DefaultController$1.run(DefaultController.java:246)
   at org.olat.core.logging.activity.ThreadLocalUserActivityLoggerInstaller.runWithUserActivityLogger(ThreadLocalUserActivityLoggerInstaller.java:108)
   at org.olat.core.gui.control.DefaultController.dispatchEvent(DefaultController.java:243)
>>> stack of 3.cause::org.hibernate.exception.ConstraintViolationException: could not execute statement
-> at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:59)
   at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)
   at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111)
   at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97)
   at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:207)
   at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:45)
   at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:3313)
   at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:3550)
   at org.hibernate.action.internal.EntityDeleteAction.execute(EntityDeleteAction.java:99)
   at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:586)
   at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:460)
>>> stack of 4.cause::com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (`olat`.`o_readmessage`, CONSTRAINT `FKEF5C01E187D2FF70` FOREIGN KEY (`message_id`) REFERENCES `o_message` (`message_id`))
-> at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
   at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
   at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
   at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
   at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
   at com.mysql.jdbc.Util.getInstance(Util.java:408)
   at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:935)
   at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3970)
   at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3906)
   at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2524)
   at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2677)