Problem with "Classification"

[jbaumann]

Hi,

I have a medium-large library of books. For some time now, if I try to enter something into the classification field without "[1]" (or some other number) I get the following error:
calibre, version 6.0.0
ERROR: Failed to set data: Could not set data, click "Show details" to see why.

Traceback (most recent call last):
  File "calibre/gui2/library/models.py", line 1217, in setData
  File "calibre/gui2/library/models.py", line 1243, in _set_data
  File "calibre/gui2/library/models.py", line 1190, in set_custom_column_data
  File "calibre/db/legacy.py", line 728, in get_next_cc_series_num_for
  File "calibre/db/cache.py", line 77, in call_func_with_lock
  File "calibre/db/cache.py", line 1834, in get_next_series_num_for
TypeError: '<' not supported between instances of 'NoneType' and 'float'

I have a second field "series" in which the same works without problems.

What can I do to fix this?

And thanks again for this fantastic software.

Cheers, Joe

[kovidgoyal]

This will fix it: https://github.com/kovidgoyal/calibr...f5af8dd2567653