IsADirectoryError when adding books on macOS 12.1

[tlf]

Thís happens when I use the 'Add books' button. If I use drag and drop nothing happens (book ignored/not added). I also tried on the .epub file, right-click->open with Calibre but this just brings Calibre into focus.

calibre, version 5.34.0
WARNING: Errors while adding: There were problems adding some files, click "Show details" for more information


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Failed to add the file /Users/i/Downloads/title.epub to the book: /Users/i/Downloads/title
With error:
Traceback (most recent call last):
  File "calibre/gui2/add.py", line 488, in add_formats
  File "calibre/db/cache.py", line 1573, in add_format
IsADirectoryError: [Errno 21] Is a directory: '/Users/i/Downloads/title.epub'

calibre Debug log
calibre 5.34  embedded-python: True is64bit: True
macOS-10.16-x86_64-i386-64bit Darwin ('64bit', '')
('Darwin', '21.2.0', 'Darwin Kernel Version 21.2.0: Sun Nov 28 20:29:10 PST 2021; root:xnu-8019.61.5~1/RELEASE_ARM64_T8101')
Python 3.8.5
OSX: ('10.16', ('', '', ''), 'x86_64')
Interface language: None
calibre 5.34  embedded-python: True is64bit: True
macOS-10.16-x86_64-i386-64bit Darwin ('64bit', '')
('Darwin', '21.2.0', 'Darwin Kernel Version 21.2.0: Sun Nov 28 20:29:10 PST 2021; root:xnu-8019.61.5~1/RELEASE_ARM64_T8101')
Python 3.8.5
OSX: ('10.16', ('', '', ''), 'x86_64')
Interface language: None
devicePixelRatio: 2.0
logicalDpi: 72.0 x 72.0
physicalDpi: 124.50000186980243 x 124.50000186980242
Using calibre Qt style: True
[0.00] Starting up...
[0.02] Initializing db...
[0.02] db initialized
[0.02] Constructing main UI...
/Users/ior/Calibre Library is not a valid directory to watch for new ebooks, ignoring
[0.61] main UI initialized...
[0.61] Started up in 0.61 seconds with 31 books
Starting QuickView
Added /Users/i/Downloads/title to db in: 0.0
Added 1 books in 0.2 seconds

[kovidgoyal]

Its not a file you are trying to add its a folder with a name that ends with .epub. Apple in their infinite wisdome decided doing this was a good idea. You will need to find a script to convert that back into an actual file.

[tlf]

Thanks kovidgoyal. I used eCanCrusher to do the job. I don't know how safe it is, but it didn't ask for any special permissions.