CantOpenError

[rfcdvc45]

Used Calibre for several years without issue. Now multiple errors when trying to add books, or tick a custom Yes/No field, or download metadata, etc., etc.

Running WIN10 Pro installed on SSD C-drive. Calibre library located on local D-drive. The "metadata.db" and "metadata_db_prefs_backup.json" files are both living in the Calibre library folder. No syncing programs in use. Windows Defender is only antivirus running. Ample free space on all drives.

Typical Errors:
ERROR: Errors while adding
ERROR: Failed to set data
ERROR: Unhandled exception (IOError:[Errno 9] Bad file descriptor)

"Restore database" tool from the Calibre library toolbar icon fails. No doubt these issues all stem from the same anomaly, i.e., "CantOpenError. "

Desperate for solution. See error details below from trying to add a book:


----------------------------------------------------------------------
Failed to add the book: Microsoft Access 2010 VBA Macro Programming 2012
D:\Downloads\Microsoft Access 2010 VBA Macro Programming 2012\Microsoft Access 2010 VBA Macro Programming 2012.pdf
With error:
Traceback (most recent call last):
File "site-packages\calibre\gui2\add.py", line 399, in add_book
File "site-packages\calibre\db\legacy.py", line 224, in create_book_entry
File "site-packages\calibre\db\cache.py", line 63, in call_func_with_lock
File "site-packages\calibre\db\cache.py", line 1556, in create_book_entry
File "site-packages\calibre\db\backend.py", line 844, in execute
File "c:\t\t\apsw-j6gj96\apsw-3.13.0-r1\src\cursor.c", line 236, in resetcursor
CantOpenError: CantOpenError: unable to open database file

[kovidgoyal]

Something, most likely an antivirus program is blocking calibre from opening the metadata.db file in its library folder.

[rfcdvc45]

Originally Posted by kovidgoyal

Something, most likely an antivirus program is blocking calibre from opening the metadata.db file in its library folder.

Thanks for responding, however that's not much help. As I said, the only antivirus I am running is Windows Defender which is pretty much baked into Windows 10. The only way to disable it is to install a third party antivirus. I can't think of any other thing that could be blocking the opening of the metadata.db file.

[BetterRed]

Originally Posted by rfcdvc45

Thanks for responding, however that's not much help. As I said, the only antivirus I am running is Windows Defender which is pretty much baked into Windows 10. The only way to disable it is to install a third party antivirus.

However, just to be sure, try excluding the calibre install directory in the Windows Defender Security Settings->Virus & threat protection settings panel - should only takes a moment to check.

Originally Posted by rfcdvc45

I can't think of any other thing that could be blocking the opening of the metadata.db file.

For diagnostic purposes only, try

• running calibre in Windows Safe Mode;
• running calibre as Administrator;
• using the CALIBRE_OVERRIDE_DATABASE_PATH Environment Variable to relocate the library database to somewhere like C:\calibre

BR

[Divingduck]

Hm. I never seen Windows Defender blocking calibre (today and in the past). Maybe something else is going wrong.

[rfcdvc45]

Originally Posted by BetterRed

However, just to be sure, try excluding the calibre install directory in the Windows Defender Security Settings->Virus & threat protection settings panel - should only takes a moment to check.


For diagnostic purposes only, try

• running calibre in Windows Safe Mode;
• running calibre as Administrator;
• using the CALIBRE_OVERRIDE_DATABASE_PATH Environment Variable to relocate the library database to somewhere like C:\calibre

BR

BetterRed, Thanks again for the suggestions. However the plot thickens as I attempted to create the exception in Defender, per your advice. When I open the install directory, "C:\Program Files\Calibre2", I notice that the files and folders therein are all screwed up. A correct install dir would have four folders (DLLs, Microsoft.VC90.CRT, plugins2, qt_plugins, & resources). Instead I have one folder named "app". Inside the "app" folder are the DLLs, qt_plugins, & resources folders, plus the "pylib.zip" file. How does this happen? I've uninstalled/reinstalled several times and the contents of the Calibre2 folder still comes out this way. And each time I get an error, "Error 1900," I think, about failure to create link/or shortcut.

See attached screenshots of Calibre2 and app folders:

I'm convinced that Defender is not blocking the metadata.db file, and I doubt that the Safe Mode/CALIBRE_OVERRIDE_DATABASE_PATH solution would resolve anything, as I the library is not on a network drive.

There must be some way I can cleanly reinstall Calibre and get the correct Calibre2 folder structure and content. But every time I try, the install dir comes up this same way. Very frustrating! What am I doing wrong?

[Divingduck]

Nothing wrong with this structure.
Here you will find some hints for a clean install:
https://manual.calibre-ebook.com/faq...is-not-working

I would suggest to run calibre first in debug mode. Maybe this will give you a bit more detail information.

[kovidgoyal]

The folder layout is correct. It was changed in calibre 3.x

The cantopenerror literally means that sqlite issued an open() system call for the metadata.db file and it failed. That can happen only because:

1) The library path points to a non-existing directory/drive/etc.
2) Something is blocking access
3) permissions on the file/directory are screwed up

I suggest you start with a new library, run calibre from a command prompt as

calibre --with-library c:\library

making sure that the folder c:\library exists and is writable by your user account.

If that works you know it is something wrong with the old library folder, if it doesn't you know it is something blocking calibre.

[BetterRed]

Originally Posted by Divingduck

Nothing wrong with this structure.

- why am I not surprised you use X2, I was about to post this



@rfcdvc45 - The install structure changed with version 3.0

I too doubt Defender is the culprit, but given its easy to exclude the calibre folder why not put that possibility to bed.

What it's more likely to be is a 3rd party program that runs at start up, or a Windows shell extension, running in Safe Mode will eliminate many of those.

And I've seen this a few times -- "blah blah' doesn't happen if I run calibre in admin mode -- I have no explanation for that, other than a Windows problem, IIRC in at least one instance it may have been solved with a system file scan.

And on a couple of occasions 'weird' problems have manifested in the 64 bit version but not in the 32 bit version, on the same machine - I have no explanation for that either. This is from the "calibre freezes/crashes" FAQ:

On some 64 bit versions of Windows there are security software/settings that prevent 64-bit calibre from working properly. If you are using the 64-bit version of calibre try switching to the 32-bit version.

BR

[Divingduck]

Originally Posted by BetterRed

- why am I not surprised you use X2, I was about to post this
BR

It look like but it's actually TotalComander. I use it since more than 20 years and it seems to be the only program since today that stay over decades of using windows systems

[theducks]

Originally Posted by rfcdvc45

Thanks for responding, however that's not much help. As I said, the only antivirus I am running is Windows Defender which is pretty much baked into Windows 10. The only way to disable it is to install a third party antivirus. I can't think of any other thing that could be blocking the opening of the metadata.db file.

Windows Defender plays nice with Calibre unless you have customized it in some unusual way.
I would look at some 'helper utilities' that you may have installed. Note: they don't need to be of the Malware kind, they just don't play nice.

[rfcdvc45]

Originally Posted by theducks

Windows Defender plays nice with Calibre unless you have customized it in some unusual way.
I would look at some 'helper utilities' that you may have installed. Note: they don't need to be of the Malware kind, they just don't play nice.

Thanks to all of you who helped me on this one. Yes, it was in fact something blocking the Calibre files, and yes, it was in fact Defender! Turns out it was a new feature in Defender that shipped with the latest Fall Creators Update v1709. The feature, which I had forgotten, and which I had enabled is called 'Controlled Folder Access.' It is supposed to help guard against potential ransomware attacks. Anyway, when I realized that this was the blocking agent, I created an exception for Calibre. Once unblocked, I created a new Calibre Library, copied back the book folders into it. And finally I had to use the 'Restore Database' tool in Calibre. Now all's well again.

You guys at MobileRead rock! Couldn't have done it without your help.

[BetterRed]

@rfcdvc45 - thanks for letting us know, karma coming your way

I have WU set to 60 days after the "suitable for business" version ships, so I'm still on 1703.

BR

[Divingduck]

@rfcdvc45 - never mind, I have this as well activated with exceptions for calibre and forgot it after I made the set up. Thanks for keep us informed.