When calling the Stack Exchange API to get the post body, it will return an error for some posts. EG:
/docs/questions#page=13&pagesize=100&fromdate=2013-09-01&todate=2013-09-02&order=asc&sort=creation&filter=!9ciXf5l7v&site=stackoverflow throws:

Invalid JSON returned

But if we exclude the post body, EG: [/docs/questions#page=13&pagesize=100&fromdate=2013-09-01&todate=2013-09-02&order=asc&sort=creation&filter=default&site=stackoverflow][2] , it works fine.

We suspect it’s because the post body contains some characters like “\0” which makes the returned JSON invalid.