haven't played around with adding to arcmap and arcpy mapping when it is not open, however, I see a potential issue. The help file suggests that when using wildcards
for df in arcpy.mapping.ListDataFrames(mxd, "t*"😞
you cycle through the list (even if it is one entry) without slicing. Your script uses
df = arcpy.mapping.ListDataFrames(mxd, "Update")[0]
and the error message suggests that there are no dataframes called "Update", so you might check this and/or use a wildcard "Update*" to see if that works. That is what the index out of range means there is no first entry in the list and the list is empty
