Problem with Calibre I cannot resolve

[quasarpod]

Hi Everyone,

I'm very much hoping someone with more expertise in Calibre than I can help me solve this problem.
When adding new books I get the following message:

Failed to add the book: The Ringworld Engineers
D:\My Documents\Larry Niven e books\Niven, Larry\The Ringworld Engineers (1807)\The Ringworld Engineers - Niven, Larry.mobi
With error:
Traceback (most recent call last):
File "site-packages\calibre\gui2\add.py", line 377, in add_book
File "site-packages\calibre\db\legacy.py", line 214, in create_book_entry
File "site-packages\calibre\db\cache.py", line 57, in call_func_with_lock
File "site-packages\calibre\db\cache.py", line 1530, in create_book_entry
File "site-packages\calibre\db\cache.py", line 1252, in set_metadata
File "site-packages\calibre\db\cache.py", line 1079, in update_path
File "site-packages\calibre\db\backend.py", line 1533, in update_path
File "site-packages\calibre\db\tables.py", line 130, in set_path
File "site-packages\calibre\db\backend.py", line 809, in execute
File "c:\cygwin64\home\kovid\sw\build\apsw-3.8.2-r1\src\cursor.c", line 231, in resetcursor
CantOpenError: CantOpenError: unable to open database file

The problem arose when using the latest version 2.72.0, but this example is from version 2.63, I restored my Win 10 Pro back to September to see if that would solve the problem.
The Calibre library is on a Synology NAS but this example was attempting to load a book from a local drive.
Library maintenance has been run but with no effect.

I would be grateful if someone can point me in the right direction.

Many thanks,
Kris

[theducks]

Read the FAQ about NAS or network shares

The last error log line says it all
(You have been bitten)

[quasarpod]

Thank you theducks for your help. That worked just fine.

[Zamboniman]

Hi,

I got this same error but the FAQ solution doesn't make sense to me. If my setup has not changed, my nas has a static ip, why is this cropping up now after years of things being stable? Sorry for the noob handholding. The whole setup has worked like a dream until this week.

Thanks

[davidfor]

Originally Posted by Zamboniman

I got this same error but the FAQ solution doesn't make sense to me. If my setup has not changed, my nas has a static ip, why is this cropping up now after years of things being stable? Sorry for the noob handholding. The whole setup has worked like a dream until this week.

You might not have changed anything about the NAS, but other things might have. Adding another computer to the network might have been enough to do it. But, the error reported is in accessing the database calibre uses to maintain the library details. The most likely thing is that this database has gotten big enough that it cannot be read fast enough over the network. Or maybe there was some other network activity that slowed things down just enough for you that the error occurred.

[Zamboniman]

Originally Posted by davidfor

You might not have changed anything about the NAS, but other things might have. Adding another computer to the network might have been enough to do it. But, the error reported is in accessing the database calibre uses to maintain the library details. The most likely thing is that this database has gotten big enough that it cannot be read fast enough over the network. Or maybe there was some other network activity that slowed things down just enough for you that the error occurred.

OK. Thank you. So the solution then is to move the whole library off the nas or is there another solution?

[theducks]

Also: Windows 10 does updates all the time. You only get to control the HOUR and not stop them (or cherry pick) what gets done.
A Calibre Library action is a transaction. Book FILES get added or removed AND the DB gets changed to reflect what is being done. This must happen synchronously. An A/V scan of qa book, might delay the file copy (eg from downloads to the Library) and the DB has been accessed now with a different timing.

[davidfor]

Originally Posted by Zamboniman

OK. Thank you. So the solution then is to move the whole library off the nas or is there another solution?

You can put the database on a local disk and use an environment variable to point to it. The instructions should be in the calibre FAQ.

[Zamboniman]

Originally Posted by davidfor

You can put the database on a local disk and use an environment variable to point to it. The instructions should be in the calibre FAQ.

Thank you for the clear and succinct answer.