Call WeChat background to obtain permanent material list interface at https://api.weixin.qq.com/cgi-bin/material/batchget_material, the returned result is:
{
"Item" : [
{
"Media_id" : "kOaThW69nNUSGSBGkVDKQrB4mX4qH4WLBu4S9plEIp0,"
"Name" : "pub_CB20190827165304916062. JPG",
"Update_time" : 1570525375,
"Url" : "http://mmbiz.qpic.cn/mmbiz_jpg/46iaTXFKXHPYZziaRkCj2adU0ZBV5qibfPfoL9GBGy6ziaRibRibcIwI83Uwh5QocUFtdkKwRVBErh7ZF98LUOyPlPmg/0? Wx_fmt=jpeg "
},
{
"Media_id" : "kOaThW69nNUSGSBGkVDKQsTxlgSqJ1grO6NnJDjsmyo,"
"Name" : "api_mpnews_cover. JPG",
"Update_time" : 1569553495,
"Url" : "","
},
],
"Total_count" : 166,
"Item_count" :
2}


This url is empty api_mpnews_cover. JPG image is returning to the list, and occupy the total number of the return, lead to the latter part of material without access to