In an upright freezer with automatic defrost, a defrost drain tube clogged with ice or gunk can cause water to puddle at the bottom of the freezer, where it forms a sheet of ice. Clear the drain tube to fix this problem.
A sheet of ice in the bottom of the freezer can be caused by a temporary power outage in a manually defrosting freezer. Water will puddle at the bottom of the freezer when ice and frost melts inside the freezer. A sheet of ice at the bottom of the freezer will form when power is restored and the puddle freezes. Defrost the freezer to get rid of the sheet of ice in the bottom of the freezer.
These repairs may help solve your upright freezer problem
Clean the freezer defrost drain tube
As part of the defrost cycle, the defrost drain tube transfers water that condenses in the evaporator drip tray to the drip pan near the compressor, where the water evaporates. Because it's directly under the evaporator, the defrost drain tube can freeze or clog. Pour hot water down the defrost drain tube to clear it.