Hi Sahana,
LEAP still has a lot of shortcomings. Even I was fed up with this error. In my case, this was happening because the LEAP was trying to calculate the scenario while it has already calculated the result for the scenario in the last simulation. So, what I am doing, I just change the global parameter lets say inflation rate whenever I am trying to recalculate the results. In this case, LEAP calculates all the results from the beginning and doesn't show the error.