Merge - is producing an error - KeyError: None

[cgrapski]

calibre, version 5.17.0
ERROR: Unhandled exception: <b>KeyError</b>:None

calibre 5.17 [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: Gather KFX-ZIP (from KFX Input) (1, 39, 0) && Package KFX (from KFX Input) (1, 39, 0) && APNX Generator (1, 1, 0) && Action Chains (1, 8, 8) && Annotations (1, 15, 0) && Audit Log (1, 0, 16) && Author Book Count (2, 2, 2) && Author Book Count Hierarchy (1, 2, 3) && Auto Datestamp and View (0, 0, 9) && Barnes & Noble (1, 2, 16) && CalibreSpy (1, 0, 84) && Clean Metadata (0, 0, 6) && Clipboard Search (1, 3, 1) && Consolidate All Library Metadata (2, 0, 40) && Count Pages (1, 11, 0) && DOC Input (1, 0, 1) && Diaps Editing Toolbag (0, 3, 7) && Drop Search Results (1, 0, 11) && English Noun Frequency (1, 0, 13) && Entities Manager (1, 0, 15) && EpubMerge (2, 11, 0) && EpubSplit (3, 0, 0) && Extract ISBN (1, 5, 0) && Extract RIS Citations (1, 0, 3) && Favourites Menu (1, 0, 5) && Find Duplicates (1, 8, 5) && Generate Cover (2, 0, 2) && GetFileName (0, 1, 1) && Goodreads (1, 5, 1) && Goodreads More Tags (1, 2, 1) && Goodreads Sync (1, 15, 1) && Goodreads_Rating (3, 1, 0) && Import List (1, 5, 4) && Job Spy (1, 0, 190) && KFX metadata reader (from KFX Input) (1, 39, 0) && KFX Input (1, 39, 0) && Kindle Collections (1, 7, 29) && Kindle hi-res covers (0, 5, 0) && KindleUnpack - The Plugin (0, 83, 0) && Library Codes (1, 0, 50) && Library Splitter (1, 0, 4) && LibraryThing Match (0, 2, 0) && Manage Series (1, 2, 11) && Mass Search-Replace (1, 0, 1) && Media File Importer (1, 0, 24) && Modify ePub (1, 6, 2) && MultiColumnSearch (1, 0, 87) && Open With (1, 5, 13) && Prince PDF (1, 5, 0) && Quality Check (1, 11, 2) && Quick Preferences (1, 5, 0) && Reading List (1, 7, 6) && Reformat plugin (2, 2, 0) && Resize Cover (1, 1, 0) && Save Composite Custom Columns (1, 1, 1) && Save To Format (0, 0, 6) && Save Virtual Libraries To Column (2, 0, 1) && Save Virtual Libraries To Column GUI (2, 3, 0) && Search The Internet (1, 8, 1) && User Category (1, 5, 5) && View Manager (1, 6, 0) && Walk Search History (1, 3, 2) && Wiki Reader (2, 2, 1) && Wikidata (2, 0, 0) && Wikidata gui (2, 0, 0) && X-Ray Creator (3, 2, 1) && Zotero Metadata Importer (1, 0, 70)
Traceback (most recent call last):
File "calibre\gui2\actions\edit_metadata.py", line 634, in merge_books
File "calibre\gui2\actions\edit_metadata.py", line 752, in merge_metadata
File "calibre\db\legacy.py", line 703, in get_custom
File "calibre\db\backend.py", line 957, in custom_field_name
KeyError: None

[kovidgoyal]

Uninstall or disable the action chains plugin.

[ownedbycats]

Originally Posted by kovidgoyal

Uninstall or disable the action chains plugin.

No, update it. It's been fixed.

[cgrapski]

Whew! Thanks both of you - I went around in circles for nearly 3 hours last night trying to figure out what could be going wrong - including fixing and reinstalling!