Hi thiago.eec,
Following up on my issue. I've managed to clean up my Calibre installation and capture a clean debug log of the "Check Books" plugin failing.
The Key Finding: The plugin seems to fail silently. When I run the check, the external ACE tool appears to crash without returning any error message to the Calibre debug log.
My System:
macOS 15.7 on Apple Silicon
Calibre 8.9 (running on Python 3.11.12)
Node.js is installed at /usr/local/bin/node
What I've Confirmed:
The problem occurs on all EPUBs, including the DRM-free Calibre "Quick Start Guide."
Calibre has Full Disk Access.
I have a clean plugin environment after removing several old, incompatible Python 2 plugins.
I am launching Calibre from the terminal (calibre-debug -g) to ensure the correct PATH is used.
Please see the complete, clean debug log below. It captures Calibre starting up, me running the check (which produces the "Invalid EPUB" error in the GUI), and then me shutting Calibre down. As you can see, after the startup sequence, no specific error from your plugin is logged to the console.
--- CALIBRE DEBUG LOG (from startup through the error) ---
Spoiler:
Last login: Wed Aug 27 16:30:19 on ttys000
rapaz@Mac ~ % /Applications/calibre.app/Contents/MacOS/calibre-debug -g
calibre 8.9 embedded-python: True
macOS-15.7-arm64-arm-64bit Darwin ('64bit', '')
('Darwin', '24.6.0', 'Darwin Kernel Version 24.6.0: Mon Aug 11 21:11:04 PDT 2025; root:xnu-11417.140.69.701.11~1/RELEASE_ARM64_T6031')
Python 3.11.12
OSX: ('15.7', ('', '', ''), 'arm64')
Interface language: None
EXE path: /Applications/calibre.app/Contents/MacOS/calibre-debug
Integration status: True
----------------------------------- REMARKABLE PLUGIN web interface ------------------------
Successfully initialized third party plugins: Gather KFX-ZIP (from KFX Input) (2, 26, 2) && DeDRM (10, 0, 9) && Package KFX (from KFX Input) (2, 26, 2) && Apple Books covers (1, 1, 0) && Barnes & Noble (1, 5, 7) && BookFusion Plugin (0, 8, 1) && Check Books (0, 2, 0) && Count Pages (1, 13, 7) && Extract ISBN (1, 6, 5) && Fantastic Fiction (1, 7, 2) && Find Duplicates (1, 10, 9) && Goodreads (1, 8, 3) && Goodreads More Tags (1, 2, 1, 2) && Goodreads Sync (1, 16, 11) && Hardcover (0, 2, 3) && ISFDB3 (1, 4, 2) && KFX metadata reader (from KFX Input) (2, 26, 2) && From KFX (2, 26, 2) && KFX Input (2, 26, 2) && Set KFX metadata (from KFX Output) (2, 17, 1) && KFX Output (2, 17, 1) && KOReader Sync (0, 7, 2) && Kindle hi-res covers (0, 5, 1) && KindleUnpack - The Plugin (0, 83, 8) && Kobo Metadata (1, 12, 0) && Kobo Utilities (2, 24, 2) && Obok DeDRM (10, 0, 9) && OverDrive Libby (0, 2, 3) && Overdrive Link (2, 58, 0) && Quality Check (1, 14, 2) && Resize Cover (1, 2, 1) && ScrambleEbook (0, 6, 0) && SmartEject (2, 6, 0) && WordDumb (3, 33, 3) && remarkable-calibre-usb-device (0, 1, 2)
QPA platform: cocoa
devicePixelRatio: 1.0
logicalDpi: 72.0 x 72.0
physicalDpi: 255.00000382971584 x 255.00000382971578
ApplicationPaletteChange event ignored
Using calibre Qt style: True
[0.00] Starting up...
[0.03] Showing splash screen...
[1.20] splash screen shown
[1.20] Initializing db...
[1.25] db initialized
[1.25] Constructing main UI...
[1.84] [DEBUG] [koboutilities.config:<module>:75] CreateNewCustomColumn is supported
DEBUG: 0.0 obok::utilities.py - loading translations
DEBUG: 0.0 obok::dialogs.py - loading translations
DEBUG: 0.0 obok::config.py - loading translations
DEBUG: 0.0 obok::action_err.py - loading translations
qt.webengine.QWebEngineView OK
qt.gui.imageio: libpng warning: iCCP: known incorrect sRGB profile
DEBUG: 0.0 koreader:action:KoreaderAction:genesis:start
[2.20] [DEBUG] [koboutilities.action:KoboUtilitiesAction.genesis:1 21] Running in optimized mode
Failed to load resource: 'commit.txt' from the plugin zip file: /Users/rapaz/Library/Preferences/calibre/plugins/OverDrive Libby.zip
Traceback (most recent call last):
File "calibre/customize/zipplugin.py", line 46, in get_resources
File "zipfile.py", line 1527, in read
File "zipfile.py", line 1564, in open
File "zipfile.py", line 1493, in getinfo
KeyError: "There is no item named 'commit.txt' in the archive"
[overdrive_libby/0.2.3] Loaded 0 items from file cache /Users/rapaz/Library/Preferences/calibre/plugins/overdrive_libby.libraries.json
DEBUG:calibre_plugins.overdrive_libby:Loaded 0 items from file cache /Users/rapaz/Library/Preferences/calibre/plugins/overdrive_libby.libraries.json
[overdrive_libby/0.2.3] Loaded 0 items from file cache /Users/rapaz/Library/Preferences/calibre/plugins/overdrive_libby.media.json
DEBUG:calibre_plugins.overdrive_libby:Loaded 0 items from file cache /Users/rapaz/Library/Preferences/calibre/plugins/overdrive_libby.media.json
qt.gui.imageio: libpng warning: iCCP: known incorrect sRGB profile
qt.svg: Cannot open file '/Users/rapaz/Library/Preferences/calibre/resources/images/WordDumb/starfish.svg', because: No such file or directory
qt.svg: Cannot open file '/Users/rapaz/Library/Preferences/calibre/resources/images/WordDumb/starfish.svg', because: No such file or directory
[2.49] GUI main window shown
[2.55] [DEBUG] [koboutilities.config:get_library_config:641] library_config: {'SchemaVersion': 1,
'profiles': {},
'readingPositionChangesStore': {'selectBooksInLibrary': False,
'updeateGoodreadsProgress': False},
'shelvesColumn': None}
[2.55] [DEBUG] [koboutilities.action:KoboUtilitiesAction.device_dr iver_name:759] could not load extended driver. Exception= No module named 'calibre_plugins.kobotouch_extended'
[2.55] [DEBUG] [koboutilities.action:KoboUtilitiesAction.set_toolb ar_button_tooltip:181] setting to text='Utilities to use with Kobo ereaders
Driver: KoboTouch'
[2.60] main UI initialized...
[2.60] Hiding splash screen
[2.65] splash screen hidden
[2.65] Started up in 2.65 seconds with 1315 books
2025-08-27 16:33:57.756 calibre-debug[30679:720574] TSMSendMessageToUIServer: CFMessagePortSendRequest FAILED(-1) to send to port com.apple.tsm.uiserver
2025-08-27 16:33:57.757 calibre-debug[30679:720574] TSMSendMessageToUIServer: CFMessagePortSendRequest FAILED(-1) to send to port com.apple.tsm.uiserver
0:00:02.092398
2025-08-27 16:33:59.865 calibre-debug[30679:720574] TSMSendMessageToUIServer: CFMessagePortSendRequest FAILED(-1) to send to port com.apple.tsm.uiserver
2025-08-27 16:33:59.865 calibre-debug[30679:720574] TSMSendMessageToUIServer: CFMessagePortSendRequest FAILED(-1) to send to port com.apple.tsm.uiserver
2025-08-27 16:33:59.865 calibre-debug[30679:720574] TSMSendMessageToUIServer: CFMessagePortSendRequest FAILED(-1) to send to port com.apple.tsm.uiserver
[51.58] Shutdown starting...
[53.83] Shutdown complete, quitting...
rapaz@Mac ~ %
This seems to point to an incompatibility between the ACE tool and the macOS/Apple Silicon environment. Any help you can provide would be greatly appreciated. Thanks!