[xwiki-users] Filesystem porter issue (VoidAttachmentVersioningStore)

Hi, Like described in http://jira.xwiki.org/browse/XWIKI-13348 I get a red line on VoidAttachmentVersioningStore. I have double-checked the configuration (those three lines in xwiki.cfg). Could someone give a hand ? Is it safe to run the backup script like this anyway ? PS: I've also attached a screenshot of the error in the issue Thanks