Calibre 3.39.1 doesn't recognize EPUB format

[randy@asa3.org]

Our small non-profit organization has five office computers, three of which have Calibre installations which we have been using successfully for several years to create epub and mobi editions of our quarterly journal. After upgrading all three to version 3.39.1, two of the computers work well but one computer, the one most often used, cannot reliably recognize a file with filetype epub. The other two computers can easily add epub files from our shared directory but when this computer adds the very same epub files from the same directory, a few are added (but are then not recongized or displayed as EPUB files!!) but then it gives an error when trying to add additional epub files. The error report is as follows below. I have tried uninstalling and reinstalling and repairing and checking all settings to be sure they are the same. What else can I do?

Randy

calibre, version 3.39.1
ERROR: Errors while adding: Failed to add any books, click "Show details" for more information


----------------------------------------------------------------------
Failed to add the book: PSCF3-19p01-02Peterson
H:\JASA\m19\epub\PSCF3-19p01-02Peterson.epub
With error:
Traceback (most recent call last):
File "site-packages\calibre\gui2\add.py", line 413, 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 1567, in create_book_entry
File "site-packages\calibre\db\cache.py", line 1287, in set_metadata
File "site-packages\calibre\db\cache.py", line 1113, in update_path
File "site-packages\calibre\db\backend.py", line 1574, in update_path
File "site-packages\calibre\db\tables.py", line 136, in set_path
File "site-packages\calibre\db\backend.py", line 845, in execute
File "c:\t\t\apsw-0ea1mm\apsw-3.26.0-r1\src\cursor.c", line 236, in resetcursor
CantOpenError: CantOpenError: unable to open database file

[theducks]

CantOpenError: CantOpenError: unable to open database file

Has nothing to do with EPUB (or any other format)

Are you running with the Library on a Network share (or NAS)?
Well, it finally bit you.
The FAQ has had an entry against this for as long as I can remember.

https://manual.calibre-ebook.com/faq...rked-drive-nas

If multiple people need ACCESS to the Library, run the content server on one PC and have the rest use their browser to get or read the books

[randy@asa3.org]

Yes, indeed, we are accessing a NAS file server. We had no idea. It's been working great for several years. Usually only one person accesses that particular directory but it is accessible to others.

I will test this tonight and see if it solves the problem and let you know. I thank you so much for pointing this out.

Randy

[chaley]

Originally Posted by theducks

CantOpenError: CantOpenError: unable to open database file

Has nothing to do with EPUB (or any other format)

The anti-virus or a file sync program on the offending computer can also cause this problem.

[randy@asa3.org]

Thank you both for the suggestions. I copied the folder with the files to the desktop and also turned off the Norton anti-virus. Still the same error. I also tried the computer which was working (but had also accessed files from the desktop) and added the exact same files from the mapped network drive on the NAS file server and had no difficulty.

So I'm back to square one. Any more ideas?

Randy

[goldilocks]

Are all 3 computers running the same Operating system?
Since the 1 is not working correctly is the one most used, does it have different programs on it (from the other 2)? Did you check the file associations for ePub? Are all 3 computers trying to access the same files at the same time? Did you run a virus scan - just in case?

I'm just a novice here, but I check a lot of things when I run into computer issues.

[higgs]

Originally Posted by randy@asa3.org

I copied the folder with the files to the desktop

Is this the folder with the files you are trying to add or the folder where your Calibre Library is?

The issue with using Calibre on a NAS is not so much where the files you are adding are stored but more to do with where your Calibre Library is stored.


CantOpenError: CantOpenError: unable to open database file

This would indicate that the issue is that your Calibre Library (and database) is on a shared drive, or that something else is locking/blocking it.

Move the Calibre Library to a local drive and then use the Switch library feature to link Calibre to this new library location.

[randy@asa3.org]

YES. That was the trick. Thank you, Higgs. I was thinking the problem was the source of the files but of course it makes sense that it is the library location. I created a new empty library on the computer and then it worked fine just like old times.

I am most grateful to you all for responding and helping us with what seemed like a devil of a problem.

Randy