After Hanjin Shipping went bankrupt, why were Hanjin's crew and ships forbidden to dock?

For fear of not receiving funds, ports in China, Japan, Singapore and Europe refused Hanjin's ships to dock or demanded cash payment. More than 60 container ships of Hanjin Company have been drifting in the open sea for many days, and hundreds of thousands of containers on board cannot be unloaded on time. At that time, it was close to the peak of delivery before Thanksgiving and Christmas, and Hanjin had no choice but to declare bankruptcy. These have been reported in the 58 container network, and there has been no Hanjin since then!