I guess the data that you are trying to insert is not matching the validatin of the filed that you are trying to put in .
either the field size of the source is more than the destination field
or the type of data is character and you are trying to insert it into a numeric .
but the first assumption is more likely .
try to check the field size for source and destination .
and try to send data on batches so you can see from which batch you have the error
Good luck