not 100% sure how you defined your variables “result” and “err” but it seems that one of them has to be an integer array, looking at the error phrase. My guess is “result” has to be the array, but might be wrong.
It is maybe a good idea to read up on arrays and how you define single or multi column arrays if you did not yet.
Here some idea, i only do not know what size array is expected:
private int [,] result = new int[1,10] //Can be defined in main program.
if (tbl.Query(richTextBox1.Text, out result, out err))
I’m glad it’s working now. I’m not sure, however, what is the correction you are saying needs to be made to the MW5 code? Could you post what you did to make it work? Is it something specific to VS2019?