Message Oracle PCC-00053 - FOR variable string is invalid type at line number in file string

ERRORFOR variable string is invalid type at line number in file string
CAUSEThe count variable in a FOR clause has the wrong datatype. The datatype must be NUMBER or LONG (or be compatible with NUMBER or LONG).
ACTIONCheck the declaration and check that the count variable has a datatype of NUMBER or LONG (or a compatible Oracle or host-language datatype).