I have [[fa:foo]] and [[en:foo]] both of them doesn't have Item at wikidata. interwikidata.py couldn't create new item and add these two links to it.
for example at here these pages have link to enwiki bot the bot couldn't add the to wikidata.
I checked it's code at try_to_add it returns False for some case so at line 94 we should have this code
if self.getOption('create') and (item is None or item is False):False means the item should not be created (because of an interwiki conflict). It would be nice if you provided a page where the problem can be reproduced.
Unfortunately closing this Phabricator task as no further information has been provided.
@Yamaha5: After you have provided the information asked for and if this still happens, please set the status of this task back to "Open" via the Add Action... → Change Status dropdown. Thanks!