[AT&T Samsung Galaxy Note II] Zen Arcade:
FAQ - Issues related to 4.1 to 4.3 upgrade/downgrade, etc

My files on my SD Card disappeared! or I'm out of space, but why?!?

When moving to 4.3 from 4.1 Android remaps the SD Card from /data/media to /data/media/0. All your files are still there, just inaccessible from your PC via USB connection, or from standard file managers. Root-capable file managers/explorers can still see the files and can provide a fix. See this thread for a permanent solution (assuming you are done with 4.1.x):

http://xdaforums.com/showthread.php?t=2274218

(Note that if you revert to a 4.1.x rom you will need to reverse this process).

I can't restore CWM/TWRP backups made in 4.1.2 now that I'm on 4.3 (or visa versa)

I believe this may be a variation on the above issue. try moving (not copying - as you may run out of space) your cwm or twrp backup folder from it's relative location in media to media/0 or the reverse and try your restore again.

** last note on this issue - philz recovery has an option to toggle sdcard location to media/0 which can help with seeing backups, etc - not sure about twrp

When I revert from 4.3 to 4.1 Gmail won't send messages

Go into Settings/Apps and clear data and cache for Gmail

I tried to flash the MJ4 bootloaders on top of the MK6 bootloaders already on my phone and now I get a message about kies and my phone won't boot

This is how the MK6 bootloader demonstrates its hostility toward downgrade attempts... While you may be stuck in download mode, you do not need to reflash an entire firmware package to escape. The easiest way out is to succesfully flash a custom recovery Odin package. This will clear the error condition in download mode and your phone once again boot correctly. See the recovery links in the OP to find an Odin package for your preferred custom recovery.

I'm not sure what version of bootloader I am running - how do I check?

There's a simple app called "Device Info" available on the Play Store (it's the one published by JPHILLI85) which will display your bootloader version. The only permission it requests is phone status/id. Or you can open up terminal emulator and type "getprop ro.bootloader" if you don't want to install an app (assuming you have already installed Terminal Emulator).

I would like to get back to a pure stock unrooted configuration - how do I do this?

First, if you have the MK6 bootloader this is currently not possible - at least as far as what will be displayed in download mode. If you are on MJ4 or below, the simplest way to do this is to flash back to 4.1.2 using the stock UCAMA4 Odin package, cf-auto-root, run triangle away, run SuperSU to completely remove root, boot recovery and do a factory reset. After this you have the option to take the OTA and update to UCUBMK6 if desired with stock everything - but it will be a one way trip with the previously discussed "revert locked" bootloader. This is the short version, there are guides available in the general section, which offer variations on this with different files. Note that the UCALJ2 ODIN package offers an option for those with the MK6 bootloader as it does not include the bootloader or tz files (thus is does not soft brick the phone as described above). In that scenario you stay on the MK6 bootloader so you don't get a complete revert (no ability to run triangle away, but you can get back to 4.1.2 and factory reset).

Here are links to the Odin stock packages for reverting and the relevant threads:

UCUBMK6 Downgrade to UCALJ2 (general guide - Thanks @perez6991 !)

How to OTA to 4.3 MK6 from LJ2 4.1.1 (with MK6 bootloader!) - Thanks @dicksteele !

Stock UCALJ2 ODIN package for those with MK6 bootloaders

TZ and (Optional) PARAM for those with MK6 bootloader

Stock UCAMA4 ODIN package for those with MJ4 bootloaders

General instructions for those with MJ4 bootloaders (use instructions but not files) **

** A note on this last link for those with MJ4 bootloaders - the instructions are sound, but the files provided include the LJ2 package and older versions of cf-auto-root and triangle away. Use MA4 instead and locate the current versions of the other two Chainfire apps (I've provided links in the previous sentence - for cf-auto-root make sure you grab the "SAMSUNG-SGH-I317" file) **

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How to get Screen Sharing (AllShareCast) working - http://xdaforums.com/show....php?t=2542509 (thanks to [MENTION=3664454]joshuaburnsjr[/MENTION] for tracking this down)