3821167 - Error: " The string 'null' is not allowed as a field value. Please use 'nil' or 'nothing'. Fields affected: custom19, emp_id. Employee_ID:NULL"

I have uploaded an employee import file and encountering the below error:
Error: " The string 'null' is not allowed as a field value. Please use 'nil' or 'nothing'. Fields affected: custom19, emp_id. Employee_ID:NULL".
I have checked the excel file and do not see employee id or anywhere that says "Null". I want to check on our end what's causing that error on that run number or check the uploaded file if there is Null entry on it that's giving the exception.

Why am I getting an error "The string 'null' is not allowed as a field value" while using employee import file? , KBA , CON-CA-ADM , Administration , Problem