Dspace 7.2 Thumbnail issue

[Raja muthukrishnan Ramanujam]

Hello Team,

We are using Dspace 7.2 version, we have configured thumbnail generation ImageMagick Image Thumbnail cron script, It was working earlier but recently thumbnails are not generated facing this below issue. Kindly help to resolve the issue.

The script has started
java.lang.NullPointerException
        at org.dspace.core.AbstractHibernateDAO.getHibernateSession(AbstractHibernateDAO.java:59)
        at org.dspace.core.AbstractHibernateDAO.createQuery(AbstractHibernateDAO.java:137)
        at org.dspace.content.dao.impl.ItemDAOImpl.findAll(ItemDAOImpl.java:58)
        at org.dspace.content.ItemServiceImpl.findAll(ItemServiceImpl.java:281)
        at org.dspace.app.mediafilter.MediaFilterServiceImpl.applyFiltersAllItems(MediaFilterServiceImpl.java:125)
        at org.dspace.app.mediafilter.MediaFilterScript.internalRun(MediaFilterScript.java:228)
        at org.dspace.scripts.DSpaceRunnable.run(DSpaceRunnable.java:150)
        at org.dspace.app.launcher.ScriptLauncher.executeScript(ScriptLauncher.java:154)
        at org.dspace.app.launcher.ScriptLauncher.handleScript(ScriptLauncher.java:132)
        at org.dspace.app.launcher.ScriptLauncher.main(ScriptLauncher.java:99)

Regards,

Raja