The Complete Message:
Single footing thickness cannot be less than 1/4 of the cantilever opening. (TS500 10.3.2)
It can be increased the thickness of solid and so called single footings.
Column can be enlarged to reduce cantilever opening
The single footing size can be reduced.
Select single footing, single footings.
Enter the properties.
In the general settings tab, enter the appropriate size in the Dim X and Dim Y lines.
You can change the thickness in the same place.