When importing to Batch with Importacular, you could encounter the error: "The field is too small to accept the amount of data you attempted to add. Try inserting or pasting less data." If so, this seems to be due to a free text field (such as a note, reference, gift attribute, etc.) that contains more characters than is allowed for that field in the Raiser's Edge. See this Blackbaud knowledgebase article for further information.
To resolve this, you can review your data source for a field that meets this description.