fail to save books

[Pumba]

Trying to save book (or books) to directory.

Host system - Windows 7 Pro

Error output:

calibre, version 1.42.0
WARNING: Could not save some books: Could not save some books, Click the show details button to see which ones.

Секретный маршрут
 Traceback (most recent call last):
   File "site-packages\calibre\library\save_to_disk.py", line 440, in save_serialized_to_disk
   File "site-packages\calibre\library\save_to_disk.py", line 312, in do_save_book_to_disk
 ValueError: Failed to calculate path for save to disk. Template: {author_sort}/{title}/{title} - {authors}
 Error: 'Formatter' object has no attribute 'strip_results'