Hey @apete, the check here dgraph/xidmap.go at ee0b99586ab740fbdec6da78605624c7feba2e5d · dgraph-io/dgraph · GitHub is failing because the xid is empty.
An xid can be the subject or the object in an nquad (<subject> predicate <object> format). I ran a few tests locally but it seems like we have enough checks to validate the subject/object. I believe we have some edge case conditions because of which we’re getting an empty subject/predicate.
@apete if you can share the data that causes this crash, we can try to investigate it. We don’t have a way to reproduce the crash right now.