Cronweatherflow can not open local file for writing

try deleting the
weatherflow.txt and weatherflow0.txt and weatherflow1.txt and weatherflow2.txt files
from the WD web files folder (i.e where you have that set (default is c:\wdisplay\webfiles\ ) in WD (control panel, webfiles/web page setup)

the issue might be a windows 10 permission problem
are you running as admin?