while adding subscribers in the "mass subscription" box.

Bug in Mailman version 2.1.5
>
> We're sorry, we hit a bug!
> If you would like to help us identify the problem, please email a copy
>
> of this page to the webmaster for this site with a description of what
>
> happened. Thanks!
>
> Traceback:
>
> Traceback (most recent call last):
> File "/usr/local/cpanel/3rdparty/mailman/scripts/driver", line 87, in
>
> run_main
> main()
> File "/usr/local/cpanel/3rdparty/mailman/Mailman/Cgi/admin.py", line
>
> 198, in main
> show_results(mlist, doc, category, subcat, cgidata)
> File "/usr/local/cpanel/3rdparty/mailman/Mailman/Cgi/admin.py", line
>
> 498, in show_results
> form.AddItem(membership_options(mlist, subcat, cgidata, doc, form))
> File "/usr/local/cpanel/3rdparty/mailman/Mailman/Cgi/admin.py", line
>
> 870, in membership_options
> all = [_m.encode() for _m in mlist.getMembers()]
> UnicodeError: ASCII decoding error: ordinal not in range(128)

Any ideas on this