The Ofsted report found that all areas of Doncaster's child protection services were inadequate.
The report said Doncaster could not be confident that all children known to the children and young people's services were safe.
In too many cases, professional practice was poor, management oversight ineffective and risk to children not identified or progressed.
More top news
Scotland will become the first part of the UK to ban smacking if the bill goes through.
Jeremy Corbyn has arrived in Brussels to "ensure negotiations get on track" as he accused Theresa May of "upsetting just about everybody".
The rising cost of clearing up a record number of illegally dumped items - which ranged from fridges animal carcasses - has been revealed.