Connection Closed Error

When I try and switch to a different library or close Calibre I get the following error. Suggestions on what is happening and how to fix this would be greatly appreciated.



calibre, version 2.79.1
ERROR: Unhandled exception: <b>ConnectionClosedError</b>:The connection has been closed

calibre 2.79.1 [64bit] embedded-python: True is64bit: True
Windows-8-6.2.9200 Windows ('64bit', 'WindowsPE')
('Windows', '8', '6.2.9200')
Python 2.7.9
Windows: ('8', '6.2.9200', '', 'Multiprocessor Free')
Successfully initialized third party plugins: DeDRM (6, 5, 2) && EpubMerge (2, 1, 0) && Goodreads (1, 1, 12) && MultiColumnSearch (1, 0, 69) && EpubSplit (2, 2, 0) && FictionDB (1, 0, 10) && Goodreads Sync (1, 10, 1) && Count Pages (1, 7, 0) && Amazon.com Multiple Countries (1, 0, 0) && EpubCheck (0, 1, 1) && Consolidate All Library Metadata (2, 0, 28) && KindleUnpack - The Plugin (0, 81, 3) && Find Duplicates (1, 6, 2) && Barnes & Noble (1, 2, 14)
Traceback (most recent call last):
File "site-packages\calibre\gui2\ui.py", line 998, in closeEvent
File "site-packages\calibre\gui2\ui.py", line 860, in write_settings
File "site-packages\calibre\gui2\init.py", line 618, in save_layout_state
File "site-packages\calibre\gui2\library\views.py", line 538, in save_state
File "site-packages\calibre\gui2\library\views.py", line 532, in write_state
File "site-packages\calibre\db\cache.py", line 61, in call_func_with_lock
File "site-packages\calibre\db\cache.py", line 606, in set_pref
File "site-packages\calibre\db\backend.py", line 129, in set
File "site-packages\calibre\db\backend.py", line 126, in __setitem__
ConnectionClosedError: The connection has been closed