Getting null error while uploading the csv file

[Dinesh2019]

A null error occurs when attempting to upload a CSV file. The error message only indicates a "null error" without additional details.

org : adjnpctuat
env : prod
user : dinesh@adjnpctuat

steps to reproduce :

1.Login to the org
2.Click on the admin
3.click on the upload
4.Click on the type( Adolescent enrolment) under Download sample
6.Download the file
7.enter the data in the file
8.click on the type( Adolescent enrolment) under upload
9.Upload the file

Expected result : the upload should be completed or if any error , error message should be shown
Actual result : it show null error which makes user completely blank

sample file is used :

enrolment.csv

error file :

errors-enrolment.csv