Meaning: This can be caused by: A copy/paste operation where the combined pier slab footing is pasted and the same supported member part is selected twice. -OR- Members input into the footing are deleted to less than the two members required to define the footing. Recovery: Select the footing that is in error. Click Select supported members on the Footing Controls. Select all the member systems that should be part of this footing. Click Finish (CTRL + ENTER) . Another option is to delete the footing.