After a data sync fails, you may see the following error:
ORA-12899: value too large for column (column name) (actual: xx, maximum: xx)
This error occurs when a row in the upload file contains too many characters than the field allows.
On the operation results page, download the upload file and look for the name of the column mentioned in the error. Also make note of how many characters is the limit for that column. Look at the rows for that column and try to find the row that contains too many characters. Once you have located it, you will need to eliminate that from the next upload and insure the character limit is not exceeded again.