TypeError: 'str' object is not callable

[Benjamin Wong]

Just updated to the latest version and when i tried singularly editing metadata or coverting books, an error message popsup, with the folowing details. I am running calibre 64bit on windows 10.

calibre, version 6.19.0
ERROR: Unhandled exception: <b>TypeError</b>:'str' object is not callable

calibre 6.19 embedded-python: True
Windows-10-10.0.19045-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.19045')
Python 3.10.1
Windows: ('10', '10.0.19045', 'SP0', 'Multiprocessor Free')
Interface language: None
Successfully initialized third party plugins: EpubCheck (0, 2, 4) && KePub Metadata Reader (3, 4, 3) && KePub Metadata Writer (3, 4, 3) && KePub Output (3, 6, 3) && Kobo Utilities (2, 16, 7)
Traceback (most recent call last):
  File "calibre\gui2\actions\edit_metadata.py", line 438, in edit_metadata
  File "calibre\gui2\actions\edit_metadata.py", line 461, in edit_metadata_for
  File "calibre\gui2\actions\edit_metadata.py", line 491, in do_edit_metadata
  File "calibre\gui2\metadata\single.py", line 1274, in edit_metadata
  File "calibre\gui2\metadata\single.py", line 71, in __init__
  File "calibre\gui2\metadata\single.py", line 116, in setupUi
  File "calibre\gui2\metadata\single.py", line 207, in create_basic_metadata_widgets
  File "calibre\gui2\metadata\basic_widgets.py", line 706, in __init__
  File "calibre\gui2\metadata\basic_widgets.py", line 709, in enable
  File "calibre\gui2\metadata\basic_widgets.py", line 634, in current_val
TypeError: 'str' object is not callable