Can't write to external card - rooted KitKat

[PatNY]

Charles, I have a new LG Volt phone running KitKat 4.4.2 and I can’t put books anywhere on the external SD card. It’s rooted stock, and I checked the permissions and they are fine in the “platform.xml” file. There are also many other apps currently installed writing to the external card, outside of the “Android” folder. CC is the only app I am having issues with.

The odd things is I have another LG phone set up about a year ago almost identically to this new Volt, also running KitKat 4.4.2 and CC is writing to the external card just fine – to the exact same folder location on the external card that I am now trying to write to with the new phone. This older LG phone is running CC 4.2.8.4. Thinking you might have made a very recent change to CC, I even put CC 4.2.8.4 on the new phone, but it still can’t access the card.

I also have two older Nook tablets, both running KitKat on custom CM ROMS that have been writing to the external card for well over a year without issue.

When I try to connect with the new phone to Calibre by either the content server or other methods, a message pops up saying “CC cannot connect because the following book formats are stored in a read-only folder …” When I try to manually select the folders on the external card with CC, the furthest I can browse to is the “media_rw” folder and when I click that to try to get to “external_SD” instead I get this: “There was an error with the folder chosen and it could not be opened …”

As a last resort, I could live with having to put books in only the private Android folder on the external card, but since I can’t browse to “external_SD,” I can’t even specify CC's private folder.

I'm stumped as there is nothing about this phone that I can see which is different from my other KitKat devices in terms of permissions for the external card. Can this be fixed?

--Pat

[chaley]

Originally Posted by PatNY

The odd things is I have another LG phone set up about a year ago almost identically to this new Volt, also running KitKat 4.4.2 and CC is writing to the external card just fine – to the exact same folder location on the external card that I am now trying to write to with the new phone. This older LG phone is running CC 4.2.8.4. Thinking you might have made a very recent change to CC, I even put CC 4.2.8.4 on the new phone, but it still can’t access the card.

There have been no changes to how CC handles SD cards in a very long time.

When I try to connect with the new phone to Calibre by either the content server or other methods, a message pops up saying “CC cannot connect because the following book formats are stored in a read-only folder …”

This means that Android told CC that CC is not allowed to write the folder. There is nothing CC can do about that.

When I try to manually select the folders on the external card with CC, the furthest I can browse to is the “media_rw” folder and when I click that to try to get to “external_SD” instead I get this: “There was an error with the folder chosen and it could not be opened …”

Have you checked the box in CC Settings / Other / SD Cards on Android 4.4+? My guess is yes or you wouldn't be getting as far as you are.

Like the last one, that error comes from Android. I don't know why CC is being blocked.

As a last resort, I could live with having to put books in only the private Android folder on the external card, but since I can’t browse to “external_SD,” I can’t even specify CC's private folder.

If you turn off the option mentioned above then you should be presented with the choice of using the private folder. If you are not then CC can't write it.

I suspect that the SD card was formatted on a different device. Android keeps all sorts of strange permissions for SD cards and often they cannot be moved between devices. I suggest that you uninstall CC, reformat the SD card, then reinstall CC. The device should then be able to get the permissions right.

If the above doesn't work then I am stumped. We will need to take the debug-log approach in hopes that there is more info about the error in that.

[PatNY]

Hi Charles,

Yes I have checked that box in CC to allow writing to the external card.

Have never had to use CC's private folder on the card before, so never knew that option had to be unchecked to get to it. Just tried it out and when I uncheck the box I can get to the private folder, so at least I have that option, and am relieved somewhat.

But I still prefer writing to the folders outside of the private folder. So I will be experimenting with formatting the card different ways later today. You are correct that it was formatted with different tools than the cards in my other KitKat devices, and I suspect you have hit on the cause of the problem.

Thanks for the timely assistance. I love Android devices, but sometimes I wonder what Google was thinking when they made writing to the card so difficult in KitKat.

--Pat

[PatNY]

The problem is solved, and CC is writing normally to the card now. The problem was a combination of how settings were imported into my new phone by CC and my failure to properly recognize which paths could be written to.

Long story:

When I set up my new phone with CC, I merely exported CC settings from one of my Nook tablets into the new device. Since I always set up the destination folders for books on the card the same way in all my devices, I just figured I could check “Save storage folder locations” and everything would come out on the other side fine. But this is what happened:
Folder location exported from Nook tablet …

/storage/sdcard1/My Files/CC/Books

Now here’s the folder location as imported into the new LG phone …

/mnt/ext_sdcard/My Files/CC/Books

That exact file path imported into the phone doesn’t exist in any of my Android phones, which I didn’t notice at the time. And when I saw “mnt” I just assumed it was the correct starting point to get to the external card. I can partially navigate to the external card through “mnt” but I have to go through “media_rw” first and that folder can’t be accessed via CC, even if rooted.

After I tried reformatting the card and was again met with the error messages, I realized it wasn’t the formatting at issue and took a closer look at the file paths. Only then did I realize the imported file path was totally different than the proper one on my device and that I had to go through “storage” instead.

The correct path on my LG phone is:

/storage/external_SD/My Files/CC/Books

That’s the file path entry point rooted KitKats have to use for the external card. I also have a rooted LG phone on Lollipop and CC is going through “storage” as well. So you may want to change the formula in CC so that “mnt” is not used in the future when converting SD card file paths from one device to another, as it might confuse someone else.

At any rate, all is well now.

--Pat

[chaley]

Interesting. What you have confirmed is that the path to the SD card varies from vendor to vendor. The only time CC "generates" a full path is when the user selects the private SD card folder, and even then CC gets the path from Android. In the other cases CC remembers the path the user took to get to the folder in question.

I have wondered whether saving folder locations on device 1 and using them on device 2 is a good idea. You just showed me that it isn't. I might add something to the backup/restore FAQ about this.

[PatNY]

Charles, when I imported the settings into a newly installed CC which had never been set up on my new phone, the full path as I specified in my previous post was automatically put in. I have never selected the private path to put books into.

I think the safest is not to convert full file paths from one device to another -- or at least pop up a message warning that the file paths may be different. I was not careful enough and just assumed since a full path was populated into the field, that it was valid. And that at the very least, the beginning of the file path was valid.

--Pat