Code changed in b33 :-
src/java.base/share/classes/sun/net/ftp/impl/FtpClient.java

else {
                 try {
- code = Integer.parseInt(response.substring(0, 3));
+ code = Integer.parseInt(response, 0, 3, 10);
                 } catch (NumberFormatException e) {
                     code = -1;
                 } catch (StringIndexOutOfBoundsException e) {

With this change the catch should be IndexOutOfBoundsException in place of StringIndexOutOfBoundsException