calibre-debug --export-all-calibre-data hangs at metadata.db

shayaknyc · 01-26-2026, 07:10 PM

Hey folks and Kovid,

Firstly, I want to just say, this is an immaculate piece of software, and I have been using this for literal years. It's by far one of my most prized digital assets. Every few months, I backup and archive my entire calibre library, using the following command:

Code:

calibre-debug --export-all-calibre-data [/path/to/empty/dir] all

This has been working flawlessly for years.

The last time I ran this command and it worked well was on 4 Oct 2025. I decided to run the export/backup again today, and everything appeared to be working alright, however, after the standard plugin errors, which are inconsequential, it hit the metadata.db file which is usually backs-up first, and begins the file countdown, but now it just hangs at the metadata.db. It's now been running for about 2 hours, usually by now it completes, but it's still stuck at the metadata.db file. Here's the output of my error when I run the command:

Code:

$ calibre-debug --export-all-calibre-data /home/shayaknyc/ayp/Calibre-Backup-20260126/ all
Exporting libraries: /home/shayaknyc/win-d/Users/shaya/Documents/Calibre Library to: /home/shayaknyc/ayp/Calibre-Backup-20260126/
Failed to initialize plugin: '/home/shaya/.config/calibre/plugins/ANOBII.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 202, in exec_module
  File "calibre/customize/zipplugin.py", line 198, in get_code
  File "calibre_plugins.ANOBII.__init__", line 39
        cached_cover_url_is_reliable = True
    ^
TabError: inconsistent use of tabs and spaces in indentation
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/Barnes & Noble.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 209, in exec_module
  File "calibre_plugins.barnes_noble.__init__", line 11, in <module>
    from urllib import quote
ImportError: cannot import name 'quote' from 'urllib' (/opt/calibre/lib/calibre-extensions/python-lib.bypy.frozen/urllib/__init__.pyc)
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/DOC Input.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 329, in load
calibre.customize.InvalidPlugin: The plugin at /home/shayaknyc/.config/calibre/plugins/DOC Input.zip cannot be used on linux
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/KoboBooks.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 209, in exec_module
  File "calibre_plugins.kobobooks.__init__", line 10, in <module>
    import time, re, HTMLParser
ModuleNotFoundError: No module named 'HTMLParser'
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/Read MP3 AudioBook metadata.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 209, in exec_module
  File "calibre_plugins.audiobookmetadatareader.__init__", line 8, in <module>
    from common import DEBUG
ModuleNotFoundError: No module named 'common'
/home/shayaknyc/win-d/Users/shaya/Documents/Calibre Library 0 2
metadata.db 0 2824

Nothing has changed in my environment (including the space in the source library path). I'm running Arch Linux, and running calibre v8.16.2.

Other than this, the software works great and I have no problems with this at all. This is the first time I've come across an issue like this, and I would greatly appreciate any insight or advice to resolve this so I may continue backing up my precious library. Thank you in advance!

kovidgoyal · 01-26-2026, 10:42 PM

Press ctrl+C that should interrupt it and get you a stack trace.

shayaknyc · 01-26-2026, 11:00 PM

Here's the full output with the stacktrace:

Code:

$ calibre-debug --export-all-calibre-data /home/shayaknyc/ayp/Calibre-Backup-20260126/ all
Exporting libraries: /home/shayaknyc/win-d/Users/shaya/Documents/Calibre Library to: /home/shayaknyc/ayp/Calibre-Backup-20260126/
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/ANOBII.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 202, in exec_module
  File "calibre/customize/zipplugin.py", line 198, in get_code
  File "calibre_plugins.ANOBII.__init__", line 39
        cached_cover_url_is_reliable = True
    ^
TabError: inconsistent use of tabs and spaces in indentation
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/Barnes & Noble.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 209, in exec_module
  File "calibre_plugins.barnes_noble.__init__", line 11, in <module>
    from urllib import quote
ImportError: cannot import name 'quote' from 'urllib' (/opt/calibre/lib/calibre-extensions/python-lib.bypy.frozen/urllib/__init__.pyc)
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/DOC Input.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 329, in load
calibre.customize.InvalidPlugin: The plugin at /home/shayaknyc/.config/calibre/plugins/DOC Input.zip cannot be used on linux
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/KoboBooks.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 209, in exec_module
  File "calibre_plugins.kobobooks.__init__", line 10, in <module>
    import time, re, HTMLParser
ModuleNotFoundError: No module named 'HTMLParser'
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/Read MP3 AudioBook metadata.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 209, in exec_module
  File "calibre_plugins.audiobookmetadatareader.__init__", line 8, in <module>
    from common import DEBUG
ModuleNotFoundError: No module named 'common'
/home/shayaknyc/win-d/Users/shaya/Documents/Calibre Library 0 2
metadata.db 0 2824
^CTraceback (most recent call last):
  File "calibre/db/backend.py", line 2721, in _backup_database
apsw.BusyError: not an error

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "runpy.py", line 198, in _run_module_as_main
  File "runpy.py", line 88, in _run_code
  File "site.py", line 47, in <module>
  File "site.py", line 43, in main
  File "calibre/debug.py", line 308, in main
  File "calibre/utils/exim.py", line 554, in run_exporter
  File "calibre/utils/exim.py", line 213, in export
  File "calibre/db/cache.py", line 86, in call_func_with_lock
  File "calibre/db/cache.py", line 3169, in export_library
  File "calibre/db/backend.py", line 2726, in backup_database
  File "calibre/db/backend.py", line 2720, in _backup_database
  File "contextlib.py", line 446, in __exit__
KeyboardInterrupt

kovidgoyal · 01-26-2026, 11:04 PM

That looks like something else has opened the calibre database and hence you are getting busy errors from sqlite.

shayaknyc · 01-26-2026, 11:13 PM

Quote:

Originally Posted by kovidgoyal

That looks like something else has opened the calibre database and hence you are getting busy errors from sqlite.

Code:

$ pwd
/home/shayaknyc/win-d/Users/shaya/Documents/Calibre Library
$ sudo lsof metadata.db
[sudo] password for shayaknyc:

$

I don't have calibre running, and I don't have anything else accessing the file. Same thing happens - it just hangs at metadata.db. Also, I've had calibre running in the background before when running these commands without issue, so not sure why it would throw an error now, even if I was running calibre or had something accessing this file.

kovidgoyal · 01-26-2026, 11:18 PM

See if that helps: https://github.com/kovidgoyal/calibr...0f70adda71720a

shayaknyc · 01-26-2026, 11:25 PM

Quote:

Originally Posted by kovidgoyal

See if that helps: https://github.com/kovidgoyal/calibr...0f70adda71720a

You'll forgive me, but I'm not finding the cache.py file anywhere in the /opt/calibre sub-path. Where am I supposed to apply this patch? I installed Calibre via the command-line linux installer....

Edit: is the assumption for me to reinstall calibre?

kovidgoyal · 01-26-2026, 11:30 PM

Wait for the next release or run calibre from source as described in: https://manual.calibre-ebook.com/develop.html

shayaknyc · Yesterday, 11:51 AM

Ok, so I cloned the repo, and set the CALIBRE_DEVELOP_FROM variable to the full path for the src directory. Presumably, any subsequent usage of the calibre-debug command should utilize this source tree for the python scripts, yeah? If so, the command still appears to hang in exactly the same place:

Code:

$ echo $CALIBRE_DEVELOP_FROM
/home/shayaknyc/git/calibre/src

$ calibre-debug --export-all-calibre-data /home/shayaknyc/ayp/Calibre-Backup-20260127 all
Exporting libraries: /home/shayaknyc/win-d/Users/shaya/Documents/Calibre Library to: /home/shayaknyc/ayp/Calibre-Backup-20260127
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/ANOBII.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 202, in exec_module
  File "calibre/customize/zipplugin.py", line 198, in get_code
  File "calibre_plugins.ANOBII.__init__", line 39
        cached_cover_url_is_reliable = True
    ^
TabError: inconsistent use of tabs and spaces in indentation
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/Barnes & Noble.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 209, in exec_module
  File "calibre_plugins.barnes_noble.__init__", line 11, in <module>
    from urllib import quote
ImportError: cannot import name 'quote' from 'urllib' (/opt/calibre/lib/calibre-extensions/python-lib.bypy.frozen/urllib/__init__.pyc)
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/DOC Input.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 329, in load
calibre.customize.InvalidPlugin: The plugin at /home/shaya/.config/calibre/plugins/DOC Input.zip cannot be used on linux
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/KoboBooks.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 209, in exec_module
  File "calibre_plugins.kobobooks.__init__", line 10, in <module>
    import time, re, HTMLParser
ModuleNotFoundError: No module named 'HTMLParser'
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/Read MP3 AudioBook metadata.zip'
Traceback (most recent call last):
  File "calibre/customize/ui.py", line 833, in initialize_plugins
  File "calibre/customize/ui.py", line 87, in load_plugin
  File "calibre/customize/zipplugin.py", line 310, in load
  File "importlib/__init__.py", line 126, in import_module
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "calibre/customize/zipplugin.py", line 209, in exec_module
  File "calibre_plugins.audiobookmetadatareader.__init__", line 8, in <module>
    from common import DEBUG
ModuleNotFoundError: No module named 'common'
/home/shayaknyc/win-d/Users/shaya/Documents/Calibre Library 0 2
metadata.db 0 2824
^CTraceback (most recent call last):
  File "calibre/db/backend.py", line 2721, in _backup_database
apsw.BusyError: not an error

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "runpy.py", line 198, in _run_module_as_main
  File "runpy.py", line 88, in _run_code
  File "site.py", line 47, in <module>
  File "site.py", line 43, in main
  File "calibre/debug.py", line 308, in main
  File "calibre/utils/exim.py", line 554, in run_exporter
  File "calibre/utils/exim.py", line 213, in export
  File "calibre/db/cache.py", line 86, in call_func_with_lock
  File "calibre/db/cache.py", line 3169, in export_library
  File "calibre/db/backend.py", line 2726, in backup_database
  File "calibre/db/backend.py", line 2720, in _backup_database
  File "contextlib.py", line 446, in __exit__
KeyboardInterrupt

Am I doing something wrong? I can confirm the cache.py file has the commit you reference above.

kovidgoyal · Yesterday, 11:00 PM

Stick a print statement in there to check if you are indeed running from source.

shayaknyc · Today, 02:57 PM

I added the print statement to the __init__.py file and despite the environment variable, running the calibredb command, as per the documentation in the link, did not display the print message.

Edit: for clarity, I edited ../calibre/src/calibre/__init__.py and added print("Hello, world!") to line 16 of that file, after all the import statements, and before the first if condition.

Then, I set the environment variable CALIBRE_DEVELOP_FROM to the full path /home/shayaknyc/git/calibre/src and executing echo $CALIBRE_DEVELOP_FROM displays the proper full path to the src directory. I then execute command calibredb and this is the output:

Code:

calibredb
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/ANOBII.zip'
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/Barnes & Noble.zip'
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/DOC Input.zip'
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/KoboBooks.zip'
Failed to initialize plugin: '/home/shayaknyc/.config/calibre/plugins/Read MP3 AudioBook metadata.zip'
Usage: calibredb command [options] [arguments]

calibredb is the command line interface to the calibre books database.

command is one of:
list
add
remove
add_format
remove_format
show_metadata
set_metadata
export
catalog
saved_searches
add_custom_column
custom_columns
remove_custom_column
set_custom
restore_database
check_library
list_categories
backup_metadata
clone
embed_metadata
search
fts_index
fts_search

For help on an individual command: calibredb command --help

Whenever you pass arguments to calibredb that have spaces in them, enclose the arguments in quotation marks. For example: "/some path/with spaces"

Options:
GLOBAL OPTIONS:
--library-path=LIBRARY_PATH, --with-library=LIBRARY_PATH
Path to the calibre library. Default is to use the
path stored in the settings. You can also connect to a
calibre Content server to perform actions on remote
libraries. To do so use a URL of the form:
http://hostname:port/#library_id for example,
http://localhost:8080/#mylibrary. library_id is the
library id of the library you want to connect to on
the Content server. You can use the special library_id
value of - to get a list of library ids available on
the server. For details on how to setup access via a
Content server, see https://manual.calibre-
ebook.com/generated/en/calibredb.html.

-h, --help show this help message and exit

--version show program's version number and exit

--username=USERNAME
Username for connecting to a calibre Content server

--password=PASSWORD
Password for connecting to a calibre Content server.
To read the password from standard input, use the
special value: <stdin>. To read the password from a
file, use: <f:/path/to/file> (i.e. <f: followed by the
full path to the file and a trailing >). The angle
brackets in the above are required, remember to escape
them or use quotes for your shell.

--timeout=TIMEOUT The timeout, in seconds, when connecting to a calibre
library over the network. The default is two minutes.

Created by Kovid Goyal <kovid@kovidgoyal.net>

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01-26-2026, 10:42 PM	#2
kovidgoyal creator of calibre Posts: 45,918 Karma: 29228280 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Press ctrl+C that should interrupt it and get you a stack trace.

01-26-2026, 11:04 PM	#4
kovidgoyal creator of calibre Posts: 45,918 Karma: 29228280 Join Date: Oct 2006 Location: Mumbai, India Device: Various	That looks like something else has opened the calibre database and hence you are getting busy errors from sqlite.

01-26-2026, 11:18 PM	#6
kovidgoyal creator of calibre Posts: 45,918 Karma: 29228280 Join Date: Oct 2006 Location: Mumbai, India Device: Various	See if that helps: https://github.com/kovidgoyal/calibr...0f70adda71720a

01-26-2026, 11:30 PM	#8
kovidgoyal creator of calibre Posts: 45,918 Karma: 29228280 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Wait for the next release or run calibre from source as described in: https://manual.calibre-ebook.com/develop.html

Yesterday, 11:00 PM	#10
kovidgoyal creator of calibre Posts: 45,918 Karma: 29228280 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Stick a print statement in there to check if you are indeed running from source.

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