Installed zotero, imported an endnote database (had resolved the keyword problem in endnote), but syncing does not work. Uploaded data not well-formed (Report ID: 30806fd2b2, report no 1335132819)

From previous threads I can see that this might be related to special
characters somewhere, but is there a way to find out which are the
offending entries (I have some 5,000 of them, no files attached)?

Thanks,

Jan