2 disadvantages of a series circuit

1. If one device fails the whole chain stops working, so if you have 100 light bulbs in series, if one breaks down, all of them will stop working and it will be difficult to find out the damaged one and replace it. Series connected Christmas lamps often have another Resistive element in parallel with the filament so in an event of filament being damaged the other lamps can keep on glowing.

2. If somehow the resistance of series connected devices are different they will have different voltage across them which might cause trouble if you need same voltage across all of them.

3.It is really difficult to work with Inductive and Capacitive load on series.
There is no way to control individual device, you have to turn on or off the whole series.
Although for series circuit only 1 wire is enough(assuming a close loop) which might save some money but it really is not practical so household appliances are connected in parallel.

From negative to negative