duplicity encryption unknown

Aptik will not restore my home folder data!!! (Detail below).

I am trying to use duplicity directly but when I enter the same encryption as used on aptik (it had no option for no encryption), duplicity crashes as follows:
Traceback (most recent call last):
  File "/usr/bin/duplicity", line 1532, in <module>
    with_tempdir(main)
  File "/usr/bin/duplicity", line 1526, in with_tempdir
    fn()
  File "/usr/bin/duplicity", line 1380, in main
    do_backup(action)
  File "/usr/bin/duplicity", line 1457, in do_backup
    restore(col_stats)
  File "/usr/bin/duplicity", line 722, in restore
    restore_get_patched_rop_iter(col_stats)):
  File "/usr/bin/duplicity", line 744, in restore_get_patched_rop_iter
    backup_chain = col_stats.get_backup_chain_at_time(time)
  File "/usr/lib/python2.7/dist-packages/duplicity/collections.py", line 970, in get_backup_chain_at_time
    raise CollectionsError("No backup chains found")
CollectionsError: No backup chains found
So what does aptik do with the "encryption" it gets from the user? I just used a single char.

(For information, if I hit the 'restore home data' button, the black window appears with a blinking cursor. It blinks forever and does nothing.)

I was using linux mint 17.3 cinnamon rosa when I backed up, and am using linux mint 18.2 kde plasma now.