I got a similar issue. I had the book folder open in the extra data folder. While the folder was still open, I used F2 to change the title (adding an extra dash). This is something I've done before without issues.
This time, I got an error about the folder being locked, but then the title changed anyways and I got this error upon clicking the book again:
Code:
calibre, version 6.20.0
ERROR: Unhandled error: Failed to read book data from calibre library. Click "Show details" for more information
Traceback (most recent call last):
File "calibre\db\backend.py", line 1574, in copy_cover_to
PermissionError: [Errno 13] Permission denied: 'D:\\Documents\\My Books\\Bethesda Softworks\\The Elder Scrolls II_ Daggerfall Us (810)\\cover.jpg'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "calibre\db\backend.py", line 1579, in copy_cover_to
PermissionError: [Errno 13] Permission denied: 'D:\\Documents\\My Books\\Bethesda Softworks\\The Elder Scrolls II_ Daggerfall Us (810)\\cover.jpg'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "calibre\gui2\library\models.py", line 643, in current_changed
File "calibre\gui2\library\models.py", line 620, in get_book_display_info
File "calibre\gui2\library\models.py", line 815, in cover
File "calibre\db\legacy.py", line 455, in cover
File "calibre\db\cache.py", line 1028, in cover
File "calibre\db\cache.py", line 85, in call_func_with_lock
File "calibre\db\cache.py", line 1063, in copy_cover_to
File "calibre\db\backend.py", line 1582, in copy_cover_to
Exception: Failed to open 'D:\\Documents\\My Books\\Bethesda Softworks\\The Elder Scrolls II_ Daggerfall Us (810)\\cover.jpg' with error: [Errno 13] Permission denied: 'D:\\Documents\\My Books\\Bethesda Softworks\\The Elder Scrolls II_ Daggerfall Us (810)\\cover.jpg'
Looking at the folder shows this. Both of them are empty except for an also-empty data folder. I had to get the files from my backup.
