I'm not sure whether I'm doing something wrong, but this looks like a bug to me. After doing some particular manipulations on the grid, there are some cells which I can no longer update. Attempts to update the value or formula using Formula, R1C1Formula, PutValue() all give a Null Reference Exception.
I have narrowed down the manipulations to the following example. I realize I could make this function work by doing things differently, but this is just to illustrate the problem - it is greatly simplified from what my real code does. I see no reason why these steps should cause an error. I'm using version 126.96.36.199 of Aspose.Cells.
public void Test()
var data = new object[1, 1];
data[0, 0] = 1;
var workbook = new Workbook();
var grid = workbook.Worksheets;
//first set up a formula referencing cell above this one
grid.Cells[36, 16].R1C1Formula = "=R[-1]C";
//then overwrite with data
grid.Cells.ImportTwoDimensionArray(data, 36, 16);
//now the referenced cell is messed up
grid.Cells[35, 16].PutValue("3"); //gives a null ref exception