[ownedbycats]

In 5.4.2, I got this error when selecting either Config or Execute from the book context menu.

calibre, version 5.4.2
ERROR: Unhandled exception: <b>AttributeError</b>:'dict' object has no attribute 'iteritems'

calibre 5.4.2 [64bit]  embedded-python: True is64bit: True
Windows-10-10.0.19041 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.19041')
Python 3.8.5
Windows: ('10', '10.0.19041', '', 'Multiprocessor Free')
Interface language: None
Successfully initialized third party plugins: Barnes & Noble (1, 2, 16) && Calibre Power Search Plugin (1, 7, 0) && Comments Cleaner (1, 2, 1) && Count Pages (1, 11, 0) && Drop Search Results (1, 0, 10) && Embed Comic Metadata (1, 5, 0) && EpubCheck (0, 2, 3) && EpubMerge (2, 11, 0) && Extract ISBN (1, 5, 0) && FanFicFare (3, 24, 13) && Fantastic Fiction (1, 4, 0) && Favourites Menu (1, 0, 5) && Find Duplicates (1, 8, 3) && Generate Cover (1, 5, 25) && Goodreads (1, 5, 1) && Import List (1, 5, 1) && Job Spy (1, 0, 188) && Kindle hi-res covers (0, 5, 0) && Kobo Books (1, 8, 0) && Kobo Utilities (2, 11, 8) && KoboTouchExtended (3, 4, 1) && Library Codes (1, 0, 47) && Manage Series (1, 2, 11) && Modify ePub (1, 6, 1) && MultiColumnSearch (1, 0, 85) && Open With (1, 5, 13) && Quality Check (1, 10, 1) && Reading List (1, 6, 18) && Save To Format (0, 0, 6) && SmartEject (2, 3, 0) && Sum Column (0, 3, 0) && View Manager (1, 6, 0)
Traceback (most recent call last):
  File "calibre_plugins.sum_column.action", line 146, in show_configuration
  File "calibre\customize\__init__.py", line 158, in do_user_config
  File "calibre_plugins.sum_column.__init__", line 65, in config_widget
  File "calibre_plugins.sum_column.config", line 88, in __init__
  File "calibre_plugins.sum_column.config", line 101, in _get_custom_columns
AttributeError: 'dict' object has no attribute 'iteritems'