[Xperia Arc Q&A, Help & Troubleshooting] gaslaw:
I was having the same problem with my device initially, but I was able to get rid of it. The problem you are having has to do your firmware kernel, you'll need to downgrade it before you begin the rooting process, I can provide you with step by step if you can exercise some patients

---------- Post added at 10:40 AM ---------- Previous post was at 09:57 AM ----------

ROOT YOUR ARC LT15i WITH THESE METHOD

[ 4.1.B.0.587 ] How To Root Xperia™ Smartphone [ Arc / Arc S & Ray]

Rooting your mobile may void the warranty and you are doing it at your own risk. Sony would be in no way responsible for any damage

Go to settings > Security > Mark "Unknown sources"Settings > Developer options > Mark USB debuggingSettings > Xperia > connectivity > USB connection mode > select MSC mode================================================== ================================================== ======================================

You should have

Flashtool

------Downloads------

1 ) Arc and Arc S - Kernel

4shared.com

Ray - Kernel

4shared.com

All other users - Kernel or even try the kernels for Arc S and Ray

2) Go to C:/ Drive > flashtool > firmwares > delete everything present and Put the kernel3) Run Flashtool click on the flashing icon ( left side below "file" option)Select flashmode > okSetup should be like this > select OKFollow the steps connect your mobile and flash.Flashtool may show error after flashing kernel, no worries. Even your build number, android version won't change. Everything would remain same. So please don't go to phone settings to check anything4) After flashing restart your device, It may not start completely, may remain at Sony logo or blank/black.Whatever the status is, just restart your device and proceed with the rooting--->( Make sure you close flashtool before running the rooting toolkit )Now connect your mobile to PC and Root Your PhoneIf you face problem in downloading the toolkit then here it is

[ READ THE FOLLOWING CAREFULLY! ]

This script will:__________1.root ur device using "andorid emulator" trick2.install Busybox (1.18.4)3.install SU files (ICS specific)4.do some checks for free space, tmp directory (will remove Google Maps if required)Before u begin:___________1.make sure u have installed adb drivers for ur device2.enable "USB DEBUGGING" - from (Menu\Settings\Developer Options\Development)3.enable "UNKNOWN SOURCES" - from (Menu\Settings\Security)4.[OPTIONAL] increase screen timeout to 10 minutes5.connect USB cable to PHONE and then connect to PC6.skip "PC Companion Software" prompt on device

[ WARNING ]make sure that no other adb server is running in background (e.g.: Flashtool, PCC, SEUS) and disable any antivirus[ How to install? ]1.extract ALL the files in the zip2.now just double click on "runme.bat"3.sit back read the on screen instructions4.the device will reboot a couple of times5.when the script finishes it will say "ALL DONE"5) Download 4.1.B.0.587 Kernels here (Links Below Arc S. 587 - Kernel

4shared.com

Arc. 587 - Kernel

4shared.com

Ray. 587 - Kernel

link 4shared

Now flash the kernel ( same procedure as step 2 and 3 above )Your mobile is now rooted (See if any Superuser app has been installed on your phone ) and back to lifeIf it's successfullCredits goes to Androxyde, Bin4ry, Doomlord

Pls if you have any issue along the line, always come back to this thread and check. This is how i got my arc rooted. pls serch for the respective software and download as am not allowed to post a link here