Do not update SudoSu on A 7.1

[Luke]

Please do not update SudoSu in the A7.1 image as it breaks the installation. 

You can permanently prevent SudoSu from nagging you about updating by following these steps: 

1. Open the Google Play Store, go to Menu -> Settings.
   
2. Tap on the "Auto-update apps" and select one of the two "Auto-update apps" options to enable it.
   
3. Go back, then go to "My apps" section, locate the app you want (e.g. anti-virus app that you mentioned) and tap on it once.
   
4. Now tap the Menu button and the first option should be the "Auto-update." Ensure the checkmark is present for this app.
   
5. For all other apps that you have installed, you will need to follow steps 3 and 4, but this time disable the "Auto-update" setting by unchecking it.
   

(source: https://android.stackexchange.com/questi...ingle-app)

[dkryder]

it might be because the su binary is in the wrong location i.e. su binary is not in directory that supersu uses there can only be one su on an android install for it to work properly. chainfire, the author of supersu, which is the package we are discussing places the binary in the directory /su/bin . different devs have been putting it in /system/bin. or /system/xbin or /su/bin or /su/xbin. you should locate where the su binary is. if the su binary is in /su/bin then the install is "standard" systemless install. if su is in one of the /system subdirectories the the build has the older system install. you can try to just replace the binary with a newer su binary.

[Wizzard]

it might be because the su binary is in the wrong location i.e. su binary is not in directory that supersu uses there can only be one su on an android install for it to work properly. chainfire, the author of supersu, which is the package we are discussing places the binary in the directory /su/bin .  different devs have been putting it in /system/bin. or /system/xbin or /su/bin or /su/xbin. you should locate where the su binary is. if the su binary is in /su/bin then the install is "standard" systemless install.  if su is in one of the /system subdirectories the the build has the older system install. you can try to just replace the binary with a newer su binary.

I have su in /system/xbin, so I should replace it by what?

[pfeerick]

See if you can get hold of the new binary and replace the one in /system/xbin. Ideally, it sounds like su should be relocated to /su/bin where it's supposed to go, or somehow configured so that when it updates it updates to the write place, but that is another story entirely

[dkryder]

try using the supersu app to "make a system app" or "install into system" because this build of android uses the /system method and it would be less difficult than trying to "unroot" via the supersu app and then trying to debug a systemless install. after supersu finishes "change to system app" then use supersu to update the binary. that has so far worked for me in the 7.1 build. issue i was having with mounting /system r/w was such that i needed to drop it for awhile.

edit: additionally install busybox i use stephen erikson's installer for busybox and also i use joey krim's root checker to verify certain aspects of a root install, also gives hints on what is wrong.

[Wizzard]

I downloaded the latest version of SuperSU apk, but there is no "su" file inside. I may try to integrate the SuperSU update to system, but dont think it will work, because I tried integrating other updates to system in Link2SD, but it did not work in A7.1.

edit: I installed busybox, then I installed supersu to system and updated su binary. It have not booted then...