An unknown error prevented deletion of book

[stumped]

Suddenly I cannot delete any book which cc has placed on my tablet.
I get the above error. Stop, restart cc soes not help.
Dunno if it is a permissions thing as books are on sd card, but they have been for months and this error is recent.
I can add books, read them, just cannot delete them. ..
Any suggestions for debugging this.
Google play store version on samsung tablet, android 6

[stumped]

Update. Seems to be an sd card glitch, connect stopped working also, said books were in a read only folder.
I re read faq, went to settings, chose the existing books folder as a new location for the books folder and "moved" books to where they already were.
All ok now.
Is my sd card about to fail or is an android permissions glitch a more likely explanation. I recently had netflix fail to playback a downloaded show from that same card. But that is also working ok after retrying dowmloads

One more posibilty. I have a clean up utility from google play called files go. That recently popped up and offered to remove junk files left behind by apps, and I agreed to,let it do that. Could that have wiped something that affected cc permission to write to sd card ?

I am now googling for ways to check sd card from within android but no luck. I think I will just download some more netflix to it and see how that does. I don't wna to unmount it as I have many apps installed to sd card to save space since I only have 16bg and can't delete samsung bloat ware from that

[chaley]

Originally Posted by stumped

Update. Seems to be an sd card glitch, connect stopped working also, said books were in a read only folder.
I re read faq, went to settings, chose the existing books folder as a new location for the books folder and "moved" books to where they already were.
All ok now.
Is my sd card about to fail or is an android permissions glitch a more likely explanation. I recently had netflix fail to playback a downloaded show from that same card. But that is also working ok after retrying dowmloads

I doubt that the SD card is failing. Android Storage Access Facility (SAF) permissions are notoriously fragile. They often disappear when Android is updated. They sometimes disappear when a device is rebooted. They occasionally disappear when the moon is full.

As for "files go": I doubt it has anything to do with the problem unless you have rooted your device. I can imagine one way that it could affect permissions, unmounting and remounting the SD card, but I think that doing that would trigger all sorts of popups and warnings.

[stumped]

Ok thanks. Other folders on the SD card seem ok.
Most likely is that somehow the app's storage permissions got corrupted.
I did the safe thing of uninstalling and then reinstalling cc and also moved the books folders and the books back to main storage. I was pleased that moon reader somehow coped with all of that and books reopened at previous last page. So I just had to reauthorise cc to use my Dropbox.
I did message Google files go app team to say I think your junk files cleaner may have broken stuff.. will update here if I get a reply.
I only keep a small selection of books actually on the tablet so this was not too onerous.
A quick search of Amazon orders says the card is 17 months old so out of warranty but only cost £10. It is a Samsung 32gb card in a Samsung tablet.
I note that the files go app tells me it can save space in "calibre companion media " but does not say how, so I pass on that, in case it helpfully deletes books that I have not recently opened

I think I will leave cc in main storage. I can manually move most apps, cc included, to sd card via settings , one app at a time, but they revert to main whenever Google play updates them. Maybe cc does not like being moved like that ?

[stumped]

ps one more comment then I will leave it.
the 1st lime this happened ( I'd just finished reading a book in Moon + ) I thought maybe Moon had marked the file as still in use., but then I checked with a different book that had been downloaded to CC but not started, so never read, and got the same result ( an unknown error is preventing... ). it could be that CC had lost storage access permission for its own metadata database, somehow- unsure where that is kept

it was next day that I realised that an attempt i CC to "connect" to cloud also gave a message about folders begin read only and refused to connect. I could nit pick & say that it should still allow connect for look but not touch... but OTOH it was good to have confirmation of what the issue was, and was more informative than " an unknown error is preventing... "

NB I was able to delete the problem book(s) using moon reader to do the delete or using Xplore, so it seems only CC has gotten its permissions corrupted

So I will stop there, while it is all working again. the only thing that could be worth testing is whether the permissions corruption can be forced to re-occur in android 6 by going to android settings and moving the CC app from main storage to SD card, and back again while the app is in various states ( like still connected, or with a book being read via CC in Moon+

files GO is a google app
https://support.google.com/filesgo/answer/7568243?hl=en
Clear your junk files
Some apps store temporary files. You can free-up space on your device by clearing these files. App settings aren’t affected.

On your Android device, open Files Go Files Go.
At the bottom-left, tap Clean .
On the 'Junk Files' option, tap Free up.
Next to 'Free up', you’ll see the amount of space that you’ll save.
Choose the apps whose files you’d like to clear.
Tap Clear.