Getting error when exporting reports

Hi,
when I export a report from katalon. i get the below error.Actually i trying to export a summary report of 250 test cases.

An internal error occurred during: “Export test suite report”.
com.fasterxml.aalto.WFCException: Illegal character (NULL, unicode 0) encountered: not valid in any content
at [row,col {unknown-source}]: [54854,2]