Bus topology has some disadvantages. When there is heavy traffic on cables then bus topology will not work properly. Sometime due to heavy traffic network may stop working. (blurtit)

With the Bus topology, all workstations are connect directly to the main backbone that carries the data. Traffic generated by any computer will travel across the backbone and be received by all workstations. This works well in a small network of 2-5 computers, but as the number of computers increases so will the network traffic and this can greatly decrease the performance and available bandwidth of your network. (firewall.cx)

To avoid signal reflection, a physical bus topology requires that each end of the physical bus be terminated. (brainbell.com)