[Metadata Source Plugin] Kobo Metadata - Page 16

DNSB · 08-01-2026, 04:45 PM

Quote:

Originally Posted by GalacticHull

Ah. You're using it with Kobo Utilities. Despite using a Kobo device, I don't run Kobo Utilities. I use calibre as a library system more than for device library management, which I prefer to do manually.

Setting it up as you have, does it change the metadata in the ebook file itself? Or does it simply change the metadata in the textfields and opf? That is, set up as you have it, would it export to a folder directory with the subtitle... and not modify the ebook?

Thank you

The metadata in the ePub file itself is changed by calibre adding it's own entry to the .opf file. <meta name="calibre:user_metadata:#subtitle" etc. However this is not a part of the standard metadata since ePub2 does not support subtitles. ePub3 does however very few ereaders handle a structure such as <meta property="title-type" refines="#subtitle">subtitle</meta>.

What the Kobo driver does is to write the subtitle into the database entry for the ePub. This does require a second connection since the database entry is created as part of the import procedure.

The subtitle field being added to the Kobo Utilities was just to keep it as close as possible to the one used by the Kobo driver.

My template for storing books on my Kobos does not use the subtitle. I try to keep the filenames as short as possible to avoid having them truncated.

Code:

Ebooks/{author_sort:sublist(0,1,&)}/{title} - {authors:sublist(0,1,&)}

Ebooks is a directory in the root of my Kobos' exposed storage. Under that directory, directories are created based on the first author in the author-sort list (that is what the sublist(0,1,&) does) with the filename inside the directory based on the title followed by the first author in the authors list.

This was required when I was finding that some books required too many characters for the title and list of authors yet I like having the full list of authors available for searching. calibre uses a maximum path length of 260 characters to keep compatibiliy across the multiple operating systems and file systems it runs with.

GalacticHull · 08-01-2026, 08:28 PM

Quote:

Originally Posted by DNSB

The metadata in the ePub file itself is changed by calibre adding it's own entry to the .opf file. <meta name="calibre:user_metadata:#subtitle" etc. However this is not a part of the standard metadata since ePub2 does not support subtitles. ePub3 does however very few ereaders handle a structure such as <meta property="title-type" refines="#subtitle">subtitle</meta>.

What the Kobo driver does is to write the subtitle into the database entry for the ePub. This does require a second connection since the database entry is created as part of the import procedure.

The subtitle field being added to the Kobo Utilities was just to keep it as close as possible to the one used by the Kobo driver.

My template for storing books on my Kobos does not use the subtitle. I try to keep the filenames as short as possible to avoid having them truncated.

Code:

Ebooks/{author_sort:sublist(0,1,&)}/{title} - {authors:sublist(0,1,&)}

Ebooks is a directory in the root of my Kobos' exposed storage. Under that directory, directories are created based on the first author in the author-sort list (that is what the sublist(0,1,&) does) with the filename inside the directory based on the title followed by the first author in the authors list.

This was required when I was finding that some books required too many characters for the title and list of authors yet I like having the full list of authors available for searching. calibre uses a maximum path length of 260 characters to keep compatibiliy across the multiple operating systems and file systems it runs with.

Thank you for taking the time to explain all this. I'm grateful

GalacticHull · 08-02-2026, 07:28 AM

Quote:

Originally Posted by DNSB

The metadata in the ePub file itself is changed by calibre adding it's own entry to the .opf file. <meta name="calibre:user_metadata:#subtitle" etc. However this is not a part of the standard metadata since ePub2 does not support subtitles. ePub3 does however very few ereaders handle a structure such as <meta property="title-type" refines="#subtitle">subtitle</meta>.

What the Kobo driver does is to write the subtitle into the database entry for the ePub. This does require a second connection since the database entry is created as part of the import procedure.

The subtitle field being added to the Kobo Utilities was just to keep it as close as possible to the one used by the Kobo driver.

My template for storing books on my Kobos does not use the subtitle. I try to keep the filenames as short as possible to avoid having them truncated.

Code:

Ebooks/{author_sort:sublist(0,1,&)}/{title} - {authors:sublist(0,1,&)}

Ebooks is a directory in the root of my Kobos' exposed storage. Under that directory, directories are created based on the first author in the author-sort list (that is what the sublist(0,1,&) does) with the filename inside the directory based on the title followed by the first author in the authors list.

This was required when I was finding that some books required too many characters for the title and list of authors yet I like having the full list of authors available for searching. calibre uses a maximum path length of 260 characters to keep compatibiliy across the multiple operating systems and file systems it runs with.

Also, you wouldn't know of a way to pick up the subtitle without having to use kobo utilities or change anything in the ebook, would you? I'm a little neurotic and don't like to change the original unless I'm fixing something specific :/

JSWolf · 08-02-2026, 10:15 AM

Quote:

Originally Posted by GalacticHull

Also, you wouldn't know of a way to pick up the subtitle without having to use kobo utilities or change anything in the ebook, would you? I'm a little neurotic and don't like to change the original unless I'm fixing something specific :/

You can do what I do. I don't have calibre make changes to the eBooks' metadata. If I wanted to change any of the metadata on my Kobo, I'd edit the metadata for the eBook's entry and use Kobo Utilities to update the metadata on my Kobo.

GalacticHull · 08-02-2026, 03:55 PM

Quote:

Originally Posted by JSWolf

You can do what I do. I don't have calibre make changes to the eBooks' metadata. If I wanted to change any of the metadata on my Kobo, I'd edit the metadata for the eBook's entry and use Kobo Utilities to update the metadata on my Kobo.

Forgive my misunderstanding.

You wrote "The metadata in the ePub file itself is changed by calibre adding it's own entry to the .opf file."

Does it change the .opf file in the calibre folder on your computers directory, or does it change the opf file in the epub itself? I'm seeking to avoid any and all changes to the file itself.

I'm not particularly adept with most technology so my vocabulary may be... insufficient to understanding.

theducks · 08-02-2026, 05:06 PM

Quote:

Originally Posted by GalacticHull

Forgive my misunderstanding.

You wrote "The metadata in the ePub file itself is changed by calibre adding it's own entry to the .opf file."

Does it change the .opf file in the calibre folder on your computers directory, or does it change the opf file in the epub itself? I'm seeking to avoid any and all changes to the file itself.

I'm not particularly adept with most technology so my vocabulary may be... insufficient to understanding.

Not unless you Polish or Embed. The LIBRARY copy does not change.
OTOH Sending to a device (using Calibre) updates that copy.
BUT Kobo does not read the metadata again. You need to use Kobo Utilities:Update Metadata in Device Library (for selected books)

GalacticHull · 08-04-2026, 06:02 PM

Quote:

Originally Posted by theducks

Not unless you Polish or Embed. The LIBRARY copy does not change.
OTOH Sending to a device (using Calibre) updates that copy.
BUT Kobo does not read the metadata again. You need to use Kobo Utilities:Update Metadata in Device Library (for selected books)

Thank you.

Also, I was well trained by cats. Unfortunately, they were all orange.

Terryw539 · 10-09-2026, 10:30 AM

I tried to install your Kobo Metadata plugin and received the following error message

calibre, version 9.16.0
ERROR: Install plugin failed: A problem occurred while installing this plugin. This plugin will now be uninstalled. Please post the error message in details below into the forum thread for this plugin and restart calibre.

Spoiler:

JSWolf · 10-21-2026, 02:59 PM

I've edited Kobo Metadata to fix the \d warning when running other plugins and looking at the log file. I've upped the version to 1.13.2.

NotSimone · 10-22-2026, 04:51 AM

Quote:

Originally Posted by JSWolf

I've edited Kobo Metadata to fix the \d warning when running other plugins and looking at the log file. I've upped the version to 1.13.2.

Can you clarify what the issue is?

NotSimone · 10-22-2026, 04:53 AM

Quote:

Originally Posted by Terryw539

I tried to install your Kobo Metadata plugin and received the following error message

calibre, version 9.16.0
ERROR: Install plugin failed: A problem occurred while installing this plugin. This plugin will now be uninstalled. Please post the error message in details below into the forum thread for this plugin and restart calibre.

Spoiler:

Sorry to say but I think something is broken with the permissions on your pc - I don't think its anything specific to this plugin. I ran into something similar a few months ago and had to reinstall windows....

DNSB · 10-22-2026, 05:38 PM

I would have to agree. The warning about the \d is just that, a warning that you are using a feature that will be deprecated. The error is the Errno 13 that you do not have permissions to access the virtual_file.log located on a volume labelled with what looks like a GUID. I'd suspect that you are attempting to use a file located in a directory to which you do not have access permissions.

One way you might quickly test this is to run calibre as administrator and see if the install error then occurs.

You can also try opening a command prompt and entering mountvol to see if you can locate the volume in the returned list. I've added the result of the command on my desktop to this message.

Code:

PermissionError: [Errno 13] Permission denied: '\\\\?\\Volume{ba5fbc33-b5dd-4468-b9fb-349269ef43b8}\\virtual_file.log'

Code:

Possible values for VolumeName along with current mount points are:

    \\?\Volume{1112909b-28c2-42bb-add6-1c223b9c647e}\
        C:\

    \\?\Volume{695ce9c4-ca5c-4031-8874-5913e54fd079}\
        *** NO MOUNT POINTS ***

    \\?\Volume{853b0a04-7ca1-4e29-98da-10bec76e7a3a}\
        D:\

    \\?\Volume{38b972d5-90c4-455b-861a-1fe6c017bddb}\
        *** NO MOUNT POINTS ***

JSWolf · Yesterday, 11:13 AM

I found the warning to be annoying. I was looking into a possible error with the Quality Check plugin and I found the log output from the warning with Kobo Metadata to be annoying. So I fixed it. I see no reason to ignore this. It just means a cleaner log and when the time comes and it's no longer a warning but an error, all will be well.

DNSB · Yesterday, 01:32 PM

Quote:

Originally Posted by JSWolf

I found the warning to be annoying. I was looking into a possible error with the Quality Check plugin and I found the log output from the warning with Kobo Metadata to be annoying. So I fixed it. I see no reason to ignore this. It just means a cleaner log and when the time comes and it's no longer a warning but an error, all will be well.

I have done much the same with some of the plugins I use. However, the important point to me is that warning would not have caused the permissions issue and so your post was not going to be helpful to the OP as the attached file did not address their issue.

dunhill · Yesterday, 04:06 PM

@Terryw539, before reinstalling anything, please check this. The error is raised inside urllib3’s create_urllib3_context(), which opens the file named in the SSLKEYLOGFILE environment variable. On your PC that variable points to a file that can’t be written (virtual_file.log). Some programs set it automatically. calibre itself doesn’t use urllib3, which is why calibre works but this plugin fails.

To check, open a Command Prompt and run:

echo %SSLKEYLOGFILE%

If it prints a path (anything other than %SSLKEYLOGFILE%), that’s the cause. To fix it:

Open Control Panel → System → Advanced system settings → Environment Variables.
Delete SSLKEYLOGFILE, checking both User and System variables.
Close calibre and delete AppData\Roaming\calibre\plugins\Ko bo Metadata.zip (note the odd space in the name, probably a leftover).
Reinstall the plugin.

If you’d like to test a build with the fix included instead, let me know and I’ll send it to you.

@NotSimone, I opened an issue on GitHub with the diagnosis and a proposed patch: https://github.com/NotSimone/Kobo-Metadata/issues/18

The patch ignores SSLKEYLOGFILE when its path isn’t writable. It also loads the network libraries on first use instead of in the constructor, so an error like this goes to the metadata log instead of uninstalling the plugin.

10-09-2026, 10:30 AM	#233
Terryw539 Junior Member Posts: 5 Karma: 10 Join Date: May 2026 Device: Kobo Libra 2	I tried to install your Kobo Metadata plugin and received the following error message calibre, version 9.16.0 ERROR: Install plugin failed: A problem occurred while installing this plugin. This plugin will now be uninstalled. Please post the error message in details below into the forum thread for this plugin and restart calibre. Spoiler: Traceback (most recent call last): File "calibre\customize\ui.py", line 827, in initialize_plugin File "calibre_plugins.kobo_metadata.__init__", line 150, in __init__ File "<frozen importlib._bootstrap>", line 1371, in _find_and_load File "<frozen importlib._bootstrap>", line 1342, in _find_and_load_unlocked File "<frozen importlib._bootstrap>", line 938, in _load_unlocked File "calibre\customize\zipplugin.py", line 224, in exec_module File "calibre_plugins.kobo_metadata.kobo_metadata", line 16, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\cloudscraper\__init__.py", line 4, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\__init__.py", line 164, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\api.py", line 11, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\sessions.py", line 15, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\adapters.py", line 80, in <module> File "C:\Users\terry\AppData\Roaming\calibre\plugins\Ko bo Metadata.zip\urllib3\util\ssl_.py", line 349, in create_urllib3_context PermissionError: [Errno 13] Permission denied: '\\\\?\\Volume{ba5fbc33-b5dd-4468-b9fb-349269ef43b8}\\virtual_file.log' During handling of the above exception, another exception occurred: Traceback (most recent call last): File "calibre\gui2\dialogs\plugin_updater.py", line 955, in _install_clicked File "calibre\customize\ui.py", line 613, in add_plugin File "calibre\customize\ui.py", line 834, in initialize_plugin calibre.customize.InvalidPlugin: Initialization of plugin Traceback (most recent call last): File "calibre\customize\ui.py", line 827, in initialize_plugin File "calibre_plugins.kobo_metadata.__init__", line 150, in __init__ File "<frozen importlib._bootstrap>", line 1371, in _find_and_load File "<frozen importlib._bootstrap>", line 1342, in _find_and_load_unlocked File "<frozen importlib._bootstrap>", line 938, in _load_unlocked File "calibre\customize\zipplugin.py", line 224, in exec_module File "calibre_plugins.kobo_metadata.kobo_metadata", line 16, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\cloudscraper\__init__.py", line 4, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\__init__.py", line 164, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\api.py", line 11, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\sessions.py", line 15, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\adapters.py", line 80, in <module> File "C:\Users\terry\AppData\Roaming\calibre\plugins\Ko bo Metadata.zip\urllib3\util\ssl_.py", line 349, in create_urllib3_context PermissionError: [Errno 13] Permission denied: '\\\\?\\Volume{ba5fbc33-b5dd-4468-b9fb-349269ef43b8}\\virtual_file.log' failed with traceback: Traceback (most recent call last): File "calibre\customize\ui.py", line 827, in initialize_plugin File "calibre_plugins.kobo_metadata.__init__", line 150, in __init__ File "<frozen importlib._bootstrap>", line 1371, in _find_and_load File "<frozen importlib._bootstrap>", line 1342, in _find_and_load_unlocked File "<frozen importlib._bootstrap>", line 938, in _load_unlocked File "calibre\customize\zipplugin.py", line 224, in exec_module File "calibre_plugins.kobo_metadata.kobo_metadata", line 16, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\cloudscraper\__init__.py", line 4, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\__init__.py", line 164, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\api.py", line 11, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\sessions.py", line 15, in <module> File "C:\Users\terry\AppData\Local\Temp\calibre-coes_o69\ssp3fe03.zip\requests\adapters.py", line 80, in <module> File "C:\Users\terry\AppData\Roaming\calibre\plugins\Ko bo Metadata.zip\urllib3\util\ssl_.py", line 349, in create_urllib3_context PermissionError: [Errno 13] Permission denied: '\\\\?\\Volume{ba5fbc33-b5dd-4468-b9fb-349269ef43b8}\\virtual_file.log' Last edited by theducks; 10-09-2026 at 08:00 PM. Reason: spoilered logs

10-22-2026, 05:38 PM	#237
DNSB Bibliophagist Posts: 55,316 Karma: 182532776 Join Date: Jul 2010 Location: Vancouver Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos	I would have to agree. The warning about the \d is just that, a warning that you are using a feature that will be deprecated. The error is the Errno 13 that you do not have permissions to access the virtual_file.log located on a volume labelled with what looks like a GUID. I'd suspect that you are attempting to use a file located in a directory to which you do not have access permissions. One way you might quickly test this is to run calibre as administrator and see if the install error then occurs. You can also try opening a command prompt and entering mountvol to see if you can locate the volume in the returned list. I've added the result of the command on my desktop to this message. Code: PermissionError: [Errno 13] Permission denied: '\\\\?\\Volume{ba5fbc33-b5dd-4468-b9fb-349269ef43b8}\\virtual_file.log' Code: Possible values for VolumeName along with current mount points are: \\?\Volume{1112909b-28c2-42bb-add6-1c223b9c647e}\ C:\ \\?\Volume{695ce9c4-ca5c-4031-8874-5913e54fd079}\ * NO MOUNT POINTS * \\?\Volume{853b0a04-7ca1-4e29-98da-10bec76e7a3a}\ D:\ \\?\Volume{38b972d5-90c4-455b-861a-1fe6c017bddb}\ * NO MOUNT POINTS * Last edited by DNSB; 10-22-2026 at 05:43 PM. Reason: Added mountvol output sample

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Yesterday, 11:13 AM	#238
JSWolf Resident Curmudgeon Posts: 85,402 Karma: 154365103 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	I found the warning to be annoying. I was looking into a possible error with the Quality Check plugin and I found the log output from the warning with Kobo Metadata to be annoying. So I fixed it. I see no reason to ignore this. It just means a cleaner log and when the time comes and it's no longer a warning but an error, all will be well.

Yesterday, 04:06 PM	#240
dunhill Wizard Posts: 1,203 Karma: 1512904 Join Date: Sep 2017 Location: Buenos Aires, Argentina Device: moon+ reader, kindle paperwhite, Linux Mint	@Terryw539, before reinstalling anything, please check this. The error is raised inside urllib3’s create_urllib3_context(), which opens the file named in the SSLKEYLOGFILE environment variable. On your PC that variable points to a file that can’t be written (virtual_file.log). Some programs set it automatically. calibre itself doesn’t use urllib3, which is why calibre works but this plugin fails. To check, open a Command Prompt and run: echo %SSLKEYLOGFILE% If it prints a path (anything other than %SSLKEYLOGFILE%), that’s the cause. To fix it: Open Control Panel → System → Advanced system settings → Environment Variables. Delete SSLKEYLOGFILE, checking both User and System variables. Close calibre and delete AppData\Roaming\calibre\plugins\Ko bo Metadata.zip (note the odd space in the name, probably a leftover). Reinstall the plugin. If you’d like to test a build with the fix included instead, let me know and I’ll send it to you. @NotSimone, I opened an issue on GitHub with the diagnosis and a proposed patch: https://github.com/NotSimone/Kobo-Metadata/issues/18 The patch ignores SSLKEYLOGFILE when its path isn’t writable. It also loads the network libraries on first use instead of in the constructor, so an error like this goes to the metadata log instead of uninstalling the plugin.