Data mapping error on member CPF5035

Message ID . . . . . . :   CPF5035  
19 -- An unexpected null field was found.   

Basically some of the fields in the Table (Physical File) defined in your RPGLE program has NULL values. To avoid this error the easiest way is to just compile the RPGLE program with this option
Allow null values  . . . . . . . ALWNULL      > *YES 

But if you interested in checking in your program if the value is NULL, then compile using option
Allow null values  . . . . . . . ALWNULL      > *USRCTL     

Then you check for the NULL field
// it's not a NULL
c                   if        not %nullind (fieldname)    
c                   endif 

// RPGLE free check for NULL
/FREE
    if  %nullind (fieldname);
        // field is null
    endif;
/END-FREE