Oh, I thought 1 zero is fine. Misread the instruction, thank you!

you cannot have zeroes in a valid/solved grid. See sudoku[4][4] = 0

edit: the tests are actually written like this, or is that you doing some tries?? xs

Check the 2nd last column. There's 2 3s in there.

i am getting "True should equal False" for above solution..

why is this not a valid slution?
[[1, 3, 2, 5, 7, 9, 4, 6, 8],
[4, 9, 8, 2, 6, 1, 3, 7, 5],
[7, 5, 6, 3, 8, 4, 2, 1, 9],
[6, 4, 3, 1, 5, 8, 7, 9, 2],
[5, 2, 1, 7, 9, 3, 8, 4, 6],
[9, 8, 7, 4, 2, 6, 5, 3, 1],
[2, 1, 4, 9, 3, 5, 6, 8, 7],
[3, 6, 5, 8, 1, 7, 9, 2, 4],
[8, 7, 9, 6, 4, 2, 1, 3, 5]]

this helped. saved my mind and time too! thank you!:)