Calibre is a wonderful tool and its the only app I use to manage my books. Thank you Kovid for creating and sharing it with us. I'm having this issues and trying everything stated before to fix the problem, but it didnt work. Here is the log if you please kindly help me. Thanks in advance.
Spoiler:
calibre, version 3.39.1
ERROR: Excepción no considerada: <b>AttributeError</b>:'NoneType' object has no attribute 'startswith'
calibre 3.39.1 embedded-python: True is64bit: False
Windows-10-10.0.17134-SP0 Windows ('32bit', 'WindowsPE')
32bit process running on 64bit windows
('Windows', '10', '10.0.17134')
Python 2.7.15+
Windows: ('10', '10.0.17134', 'SP0', u'Multiprocessor Free')
Interface language: es
Successfully initialized third party plugins: DeDRM (6, 6, 1) && Similar Stories (1, 0, 58) && Goodreads Sync (1, 12, 1) && Obok DeDRM (3, 1, 6) && Generate Cover (1, 5, 21) && Webscription (1, 1, 0) && Modify ePub (1, 3, 13) && Read MP3 AudioBook metadata (1, 0, 79) && Kindle Collections (1, 7, 21) && Anobii Fetcher (1, 1, 0) && Wiki Reader (2, 1, 0) && Copy Cover To Device (2, 0, 0) && Martinus.sk (0, 1, 1) && Moly_hu (1, 0, 4) && Libri_hu (1, 0, 6) && Goodreads (1, 2, 0) && Fantastic Fiction (1, 2, 0) && ANOBII (0, 4, 3) && Beam Ebooks (1, 0, 0) && ADLIBRIS_NO (0, 0, 9) && Quality Check (1, 9, 11) && Find Duplicates (1, 6, 3) && Consolidate All Library Metadata (2, 0, 32) && KindleUnpack - The Plugin (0, 81, 5) && ADLIBRIS_SE (0, 2, 3) && Search The Internet (1, 7, 6) && BOL_DE (0, 7, 5) && Skoob (1, 2, 1) && Fantastic Fiction Adults (1, 0, 4) && FictionDB (1, 0, 10) && catawiki (0, 0, 2) && Barnes & Noble (1, 2, 15) && KoboBooks (1, 0, 0) && Reading List (1, 6, 6)
Traceback (most recent call last):
File "site-packages\calibre\gui2\preferences\device_user_defi ned.py", line 74, in device_info
File "site-packages\calibre\gui2\preferences\device_user_defi ned.py", line 68, in fmtid
AttributeError: 'NoneType' object has no attribute 'startswith'