NPE when failing to create EventHarvest

Exception in thread "Thread-14" dk.netarkivet.common.exceptions.ArgumentNotValid: Unable to create an event harvest.
The following seeds are invalid:
http://ftp://alpha.gnu.org/gnu/gpaint/gpaint-2-0.3.2.tar.gz

        at dk.netarkivet.harvester.datamodel.PartialHarvest.addSeeds(PartialHarvest.java:312)
        at dk.kb.webdanica.core.interfaces.harvesting.SingleSeedHarvest.<init>(SingleSeedHarvest.java:126)
        at dk.kb.webdanica.webapp.workflow.HarvesterThread.run(HarvesterThread.java:32)
        at java.lang.Thread.run(Thread.java:748)
17:50:17.290 [Harvest worker-SendThread(narcana-yarn01.statsbiblioteket.dk:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Got ping response for sessionid: 0x45d78defaa201bf after 0ms
14-Aug-2017 17:50:28.107 SEVERE [Harvest worker] dk.kb.webdanica.webapp.workflow.HarvestWorkThread.harvest java.lang.NullPointerException
 java.lang.NullPointerException
        at dk.kb.webdanica.webapp.workflow.HarvestWorkThread.harvest(HarvestWorkThread.java:343)
        at dk.kb.webdanica.webapp.workflow.HarvestWorkThread.process_run(HarvestWorkThread.java:286)
        at dk.kb.webdanica.webapp.workflow.WorkThreadAbstract.run(WorkThreadAbstract.java:89)
        at java.lang.Thread.run(Thread.java:748)