Never mind, worked immediately after sending this mail ;-)
On Mon, Aug 22, 2016 at 8:37 PM Magnus Manske <magnusmanske(a)googlemail.com>
I am trying to create new items by supplying a
large-ish JSON structure,
but I keep getting "The serialization is invalid". Sadly, that does not
tell me which part is invalid.
Can anyone see what's wrong? (I suspect the references, but I don't want
to create unreferenced testing items, and test.wikidata.org