[Oddball]

when I open any epub in EDIT METADATA, once i scroll down then click the X to close i get the following error:

calibre, version 3.45.0
ERROR: Unhandled exception: <b>SystemError</b>:error return without exception set

calibre 3.45 [64bit] embedded-python: True is64bit: True
Windows-7-6.1.7601-SP1 Windows ('64bit', 'WindowsPE')
('Windows', '7', '6.1.7601')
Python 2.7.15+
Windows: ('7', '6.1.7601', 'SP1', u'Multiprocessor Free')
Interface language: None
Successfully initialized third party plugins: DeDRM (6, 5, 3) && Inept Epub DeDRM (0, 1, 7) && KePub Metadata Reader (3, 0, 2) && djvumaker (1, 0, 2) && Goodreads (1, 4, 0) && Amazon.com Multiple Countries (1, 0, 0) && Obok DeDRM (6, 5, 3) && Extract ISBN (1, 4, 4) && all recipes Recipe Reader (1, 0, 1) && Modify ePub (1, 3, 13) && View Manager (1, 4, 3) && Find Duplicates (1, 6, 3) && Set KFX metadata (from KFX Output) (1, 30, 0) && KFX Output (1, 30, 0) && Kindle Collections (1, 7, 24) && Barnes & Noble (1, 2, 15) && Library Codes (1, 0, 41)
Traceback (most recent call last):
File "site-packages\calibre\gui2\viewer\main.py", line 379, in closeEvent
File "site-packages\calibre\gui2\viewer\main.py", line 366, in shutdown
File "site-packages\calibre\gui2\viewer\main.py", line 392, in save_state
File "site-packages\calibre\utils\config.py", line 448, in __setitem__
File "site-packages\calibre\utils\config.py", line 411, in commit
File "site-packages\calibre\utils\config.py", line 432, in to_raw
File "site-packages\calibre\utils\config_base.py", line 86, in json_dumps
File "json\__init__.py", line 251, in dumps
File "json\encoder.py", line 209, in encode
File "json\encoder.py", line 434, in _iterencode
File "json\encoder.py", line 408, in _iterencode_dict
File "json\encoder.py", line 313, in _iterencode_list
File "json\encoder.py", line 39, in encode_basestring
SystemError: error return without exception set

Is it possible that one or more of the plugins are malfunctioning with this version of calibre?
This error only occurs since update from 3.44 to 3.45