Should I unlock the boot loader of Xperia U?
What are the advantages and disadvantages?
Sent from my ST25i using xda app-developers app
advantage
U can try custom roms that use a custom kernel
Disadvantage - U LOOSE WARRANTY
How to restore warranty after rooting/unlocking bootloader
Hello XDA Members,
This is my first post
I am new to android experiments but have experience of flashing microcontrollers(Programmable chips) from engineering degree. So I am comfortable with using flash tool, fastboot etc.
Recently, I have rooted, installed CWM recovery and custom rom on my Xperia U. My question is
"If I flash sony stock rom to my device, the warranty will be restored or not?"
if NOT then how can I restore the warranty before going to service centre say for some hardware issue.
Audicious said:
Hello XDA Members,
This is my first post
I am new to android experiments but have experience of flashing microcontrollers(Programmable chips) from engineering degree. So I am comfortable with using flash tool, fastboot etc.
Recently, I have rooted, installed CWM recovery and custom rom on my Xperia U. My question is
"If I flash sony stock rom to my device, the warranty will be restored or not?"
if NOT then how can I restore the warranty before going to service centre say for some hardware issue.
Click to expand...
Click to collapse
Yes it will b restored
Coz no one can tell u flashed it
One of the fellow members confirmed this
He got his hardware issue sorted out after flashing that too under warranty
---------- Post added at 05:24 PM ---------- Previous post was at 05:23 PM ----------
Btw
Welcome
Unlocking Bootloader
Is it necessary to unlock bootloader? i mean there is kernals and recovery available for Locked Bootloaders then why we go for unlocking it?
sukhera2 said:
Is it necessary to unlock bootloader? i mean there is kernals and recovery available for Locked Bootloaders then why we go for unlocking it?
Click to expand...
Click to collapse
Its not necessary.. There are ROMs for locked bootloaders too, but to try great ROMs like Cyanogen Mod you need unlocked bootloader.
you can lock the bootloader again if u wish
Related
Rooted using zerg
Installed CWM
tried to flash SE tweaked
boot loader locked
tried to resolve using flashtool, and PC companion.
but still does not help.
any other ideas?
maybe i did the flashtool and PC companion wrongly?
i havent try SEUS. where can i find SEUS?
SEUS
Try flashtool again. I have fixed every stupid mistake with flashtool
Make sure sou also check wipe user data. Try to wipe everything possible (except SD card), to make sure no errors from previous installations remain.
---------- Post added at 02:18 PM ---------- Previous post was at 02:16 PM ----------
tried to flash SE tweaked
boot loader locked
Click to expand...
Click to collapse
We'll there your problem. (in case you don't know) Custom ROMS + locked bootloader doens't go well.
i thought the bootloader was only to install CWM?
and since i have installed CWM without bootloader being unlocked, i thought i was good to go.
alright will try out SEUS.
BTW which version of flash tool, and which firmware should i be loading for the neo v?
oh anyway SEUS managed to salvage my phone!
thanks for the link!
BTW i got an off-thread question to ask, what is the differnece between rooting and unlock bootloader?
which one actually voids warranty?
serverxeon said:
what is the differnece between rooting and unlock bootloader?
which one actually voids warranty?
Click to expand...
Click to collapse
Unlocking voids warranty.
But difference between rooting and unlocking: with rooted phone you had superuser right in your phone, BUT you can't flash different roms and kernel, because for that you need access to bootloader.
Unlocking bootloader giving you FULL access your phone. And this access is so great, if you don't know what you are doing, you gonna brick your phone very easy.
Also bootloader unlocking process is giving you root permissions.
Sent via MIUI 2.1.13
serverxeon said:
oh anyway SEUS managed to salvage my phone!
thanks for the link!
BTW i got an off-thread question to ask, what is the differnece between rooting and unlock bootloader?
which one actually voids warranty?
Click to expand...
Click to collapse
Glad you fixed it!
taaviu said:
If you don't know what you are doing, you gonna brick your phone very easy.
Click to expand...
Click to collapse
Is possible to brick it and never restore it anymore? I had a samsung spica and there was someways do hard brick it, but I always avoid that ways and be carefull. Can someone make a new thread explaining some essentials things? I have my Neo for about a week now
dioggo92 said:
Is possible to brick it and never restore it anymore? I had a samsung spica and there was someways do hard brick it, but I always avoid that ways and be carefull. Can someone make a new thread explaining some essentials things? I have my Neo for about a week now
Click to expand...
Click to collapse
You can fix it anytime
Sometime it need only some credit to someone
Personally I recommended bootloader unlocking....because if you brick later your phone...fixing is much easily ....much
Sent via MIUI 2.1.13
taaviu said:
You can fix it anytime
Sometime it need only some credit to someone
Personally I recommended bootloader unlocking....because if you brick later your phone...fixing is much easily ....much
Sent via MIUI 2.1.13
Click to expand...
Click to collapse
How much? just a wipe data and reinstall a new ROM? And in what situations I can/I must/I shouldn't use SEUS? On my old samsung spica there was a kernel version that if I use ODIN with it the phone get hard bricked and unable to fix it... Some people had to send it to repair.
On my neo I have .42 completely stock for now... After unlock bootloader is it possible to get warranty back again?
By the way, thanks
dioggo92 said:
How much? just a wipe data and reinstall a new ROM? And in what situations I can/I must/I shouldn't use SEUS? On my old samsung spica there was a kernel version that if I use ODIN with it the phone get hard bricked and unable to fix it...
On my neo I have .42 completely stock for now...
By the way, thanks
Click to expand...
Click to collapse
Simple. Don't brick your phone. Before you do something..read forum, ask, analyse and then do it.
If you already unlock BL...then you can't use officials SE update tools.
But there is many other tools what working with ANY conditions BL.
Sent via MIUI 2.1.13
taaviu said:
Simple. Don't brick your phone. Before you do something..read forum, ask, analyse and then do it.
If you already unlock BL...then you can't use officials SE update tools.
But there is many other tools what working with ANY conditions BL.
Sent via MIUI 2.1.13
Click to expand...
Click to collapse
After unlock bootloader is it possible to get warranty back again?
---------- Post added at 05:30 PM ---------- Previous post was at 05:27 PM ----------
I have found this, but doesn't talk about warranty...
http://forum.xda-developers.com/showthread.php?t=1134335
dioggo92 said:
After unlock bootloader is it possible to get warranty back again?
---------- Post added at 05:30 PM ---------- Previous post was at 05:27 PM ----------
I have found this, but doesn't talk about warranty...
http://forum.xda-developers.com/showthread.php?t=1134335
Click to expand...
Click to collapse
If you locking bootlader again then YES.
Sent via MIUI 2.1.13
serverxeon said:
Rooted using zerg
Installed CWM
tried to flash SE tweaked
boot loader locked
tried to resolve using flashtool, and PC companion.
but still does not help.
any other ideas?
maybe i did the flashtool and PC companion wrongly?
i havent try SEUS. where can i find SEUS?
Click to expand...
Click to collapse
It still amazes me why people do this. Se-tweak for unlocked bootloader well glad your fixed now
Sent from my MT15i using xda premium
People do this because is a rom compatible with stock kernel and WORKS PERFECT with CWM and bl locked, tested by me and a lot of this "stubborn" people who don't want, or can't, unlock their bootloader. Solution is very simple, tweak a little your update-script and make life easy to all these people who want install your rom and enjoy your work.
Is for unlocked boot loader. Not locked to be honest it's not worth it
Still incorrect as stock is crap and no point if you use stock no tweaks no point in se tweaked
Sent from my MT15i using xda premium
right ive got a xperia mini pro and want to root it and put custom rom onto it like cm 7 cant someone help me through this please do i need to unlock the bootloader first ? if so how do i do it is it like the xperia play to unlock the bootloader ?
HI.I have this same phone.You need to unlock bootloader for flashing any kernels or custom roms.I havent done it yet because Im waiting for oficial stock ICS upgrade.You can unlock the bootloader at SE website,but you will lose your guarantee,thats the point why I dont do this.If you just root it you can change themes,flash mods and a lot more and this not going to harm your guarantee so decision is allways yours.Good luck anyway.
To install Cyanogenmod, you NEED to unlock the bootloader, because Cyanogenmod uses a different kernel. To unlock the bootloader, just go to the official SE website and follow the instructions.
SwissGeeK said:
To install Cyanogenmod, you NEED to unlock the bootloader, because Cyanogenmod uses a different kernel. To unlock the bootloader, just go to the official SE website and follow the instructions.
Click to expand...
Click to collapse
Sadly according to the sony ericsson website i cannot unlock my bootloader, does that mean I'm boned for using any rom that has a custom kernel?
http://wiki.cyanogenmod.com/wiki/Sony_Ericsson_Xperia_Mini_Pro:_Full_Update_Guide
this will help you
---------- Post added at 07:50 PM ---------- Previous post was at 07:50 PM ----------
http://wiki.cyanogenmod.com/wiki/Sony_Ericsson_Xperia_Mini_Pro:_Full_Update_Guide
this will help you
Hi!
I have an Xperia U ICS flashed using flashtool. Unrooted and Locked. I do want to root/unlock, I just had a few questions first.
- Can I root my phone WITHOUT unlocking the bootloader?.. as I heard that unlocking ones bootloader is risky and can damage the phone.
I really have no idea as to how to root a phone as I'm totally new to droid ( 1st android phone ) ! So it would be really helpful if someone at least posted a link(s) for a tutorial. (The right tutorial for a newbie! ) If possible, I want to root my phone WITHOUT unlocking the bootloader.
- What is the difference between Root with Locked bootloader & Root with Unlocked bootloader?
And regarding ROMs, I also heard that custom ROMs are really much better than the stock ones, So If anyone could help me choosing the best ROM for my Xperia U would be helpful too. Also a tutorial link as to how to install a custom ROM. User reviews would be real helpful here, People who have custom Xperia U ROMs, HELP!
Help out guys
P.S I know there are tutorials out there, I just don't know which one to follow.
Just follow the instructions here to root your phone :
http://forum.xda-developers.com/showthread.php?t=1886460
And then install cmw for your phone to install custom ROM'S
If the info helped you click the thanks button..
Sent from my LT26i
What is CMW and how to install those?! Dude you gotta be little more specific with , I'm new here!
Clockwork recovery (cmw) is to install new rom and to backup..
Follow instruction here
http://forum.xda-developers.com/showthread.php?t=1756346
If the info helped you click the thanks button
Sent from my LT26i
sunil.s125 said:
Just follow the instructions here to root your phone :
http://forum.xda-developers.com/showthread.php?t=1886460
And then install cmw for your phone to install custom ROM'S
If the info helped you click the thanks button..
Sent from my LT26i
Click to expand...
Click to collapse
sunil.s125 said:
Clockwork recovery (cmw) is to install new rom and to backup..
Follow instruction here
http://forum.xda-developers.com/showthread.php?t=1756346
If the info helped you click the thanks button
Sent from my LT26i
Click to expand...
Click to collapse
I appreciate you reply man, I also have a few other questions too in my post. You can answer them if you wish to, Or I'll just wait for someone else too. And also for the tuts.
Hi..
Dude I don't use xperia U so can't help you on rom, which ones best for your device ....
If the info helped you click the thanks button
Sent from my LT26i
Alright, I 'll just wait then.
Bootloader unlocked means u can try different roms now bt u loose ur warranty and u also need to flash a custom kernel for custom rom
Rooting I guess has nothing to do wid bootloader being locked or unlocked
Sent from my ST25i using Tapatalk 2
kushalsv said:
Hi!
I have an Xperia U ICS flashed using flashtool. Unrooted and Locked. I do want to root/unlock, I just had a few questions first.
- Can I root my phone WITHOUT unlocking the bootloader?.. as I heard that unlocking ones bootloader is risky and can damage the phone.
I really have no idea as to how to root a phone as I'm totally new to droid ( 1st android phone ) ! So it would be really helpful if someone at least posted a link(s) for a tutorial. (The right tutorial for a newbie! ) If possible, I want to root my phone WITHOUT unlocking the bootloader.
- What is the difference between Root with Locked bootloader & Root with Unlocked bootloader?
And regarding ROMs, I also heard that custom ROMs are really much better than the stock ones, So If anyone could help me choosing the best ROM for my Xperia U would be helpful too. Also a tutorial link as to how to install a custom ROM. User reviews would be real helpful here, People who have custom Xperia U ROMs, HELP!
Help out guys
P.S I know there are tutorials out there, I just don't know which one to follow.
Click to expand...
Click to collapse
Yes you can root your phone without locking the bootloader, when you unlock the bootloader you void your warranty. A locked bootloader doesnt void your warranty, but doesnt allow you to be able to flash all custom roms, some need an unlocked bootloader to work. Cannot help you with guides because i use the Xperia P, good luck though.
MadManMark said:
Yes you can root your phone without locking the bootloader, when you unlock the bootloader you void your warranty. A locked bootloader doesnt void your warranty, but doesnt allow you to be able to flash all custom roms, some need an unlocked bootloader to work. Cannot help you with guides because i use the Xperia P, good luck though.
Click to expand...
Click to collapse
Thanks!:good: Alright, So I've decided, I'll root my phone without unlocking my bootloader, So any help here please?
And are there any ROMs I can apply to a locked bootloader? Help Xperia U users please!
root without unlock bootloader it still save to be use and doesn't void your warranty
you still can try some custom ROM but definitely never to custom kernel
Hi. I'm kinda new with android phones. I have an xperia sola and it runs 4.0.4 versoin .54 ICS..and it's getting low in memory and not as fast as i was expecting. If i flash a custom rom, like the cm 9.1 ( ?? 10 ) ...will i lose my warranty ?
Yes when you unlock the bootloader
Cm10 not released yet...
Sent from my MT27i using xda premium
So...my phone says "bootloader unlock allowed : yes"...i dont know much about it...but..is it worth it to flash 9.1 or should i wait and official update from sony ?
There is no official jb for sola...
And for bootloader yes it means you can unlock the bootloader...
But it will lose ur warranty...
Sent from my MT27i using xda premium
octhunder said:
So...my phone says "bootloader unlock allowed : yes"...i dont know much about it...but..is it worth it to flash 9.1 or should i wait and official update from sony ?
Click to expand...
Click to collapse
you will loose your warranty when you unlock your BL.......
and i will say its worth to unlock your BL........
and which update are you talking abt from SONY........ you wont get any further updates for SOLA from SONY...... except for FW (that to is doubtful).....
well i'm running 6.1.1.B.1.54...and i know about .75 and .89...... btw i forgot to tell you, i already rooted the phone..with some tutorial from xda...and it says it can be unrooted if i want my warrnty back. (root with restory by bin4ry).
octhunder said:
well i'm running 6.1.1.B.1.54...and i know about .75 and .89...... btw i forgot to tell you, i already rooted the phone..with some tutorial from xda...and it says it can be unrooted if i want my warrnty back. (root with restory by bin4ry).
Click to expand...
Click to collapse
if you want to unroot the best method is to flash the stock ftf file.....
So..basicaly i still have my warranty ?
octhunder said:
So..basicaly i still have my warranty ?
Click to expand...
Click to collapse
Yup
By rooting you are not loosing warranty.Any modification done to operating system doesn't cover your phone warranty.If your phone breaks because of modification in system then your warranty will not cover that,but if it just breaks from just sitting on your table your warranty will cover that even if you are rooted or have done any software modifications.
yeah..so if i fail installing new rom...warranty bye bye..it's kinda..frustrating
warranty disappears only when you unlock the core, but if it is locked, then may or may not notice :laugh:
is it posible to flash new rom without unlocking ?
octhunder said:
is it posible to flash new rom without unlocking ?
Click to expand...
Click to collapse
you can flash roms without unlocking BL, but not CM based.....
can you recommand anything ..with tutorial ?
@[email protected] said:
you can flash roms without unlocking BL, but not CM based.....
Click to expand...
Click to collapse
no its not true ... you can have cm9 with locket bootloader also
[ROM][UNLOCKED/LOCKED] • ParanoidAndroid ™ v1.4a XSola • [UNOFFICIAL][FXP207]
Latest cm9 for locked bootloders ... try this:good:
---------- Post added at 09:51 PM ---------- Previous post was at 09:44 PM ----------
ravinder0003 said:
no its not true ... you can have cm9 with locket bootloader also
[ROM][UNLOCKED/LOCKED] • ParanoidAndroid ™ v1.4a XSola • [UNOFFICIAL][FXP207]
Latest cm9 for locked bootloders ... try this:good:
Click to expand...
Click to collapse
sorry forget to add link ...
http://forum.xda-developers.com/showthread.php?t=2080040
---------- Post added at 09:57 PM ---------- Previous post was at 09:51 PM ----------
octhunder said:
yeah..so if i fail installing new rom...warranty bye bye..it's kinda..frustrating
Click to expand...
Click to collapse
no need to worry abt the warranty status ... unlock the BL .. do whatever you want ... just relock the BL and warranty is back
just visit the link to re-lock the BL ... you can then update using official SONY update centre ...
http://forum.xda-developers.com/showthread.php?t=1920189
ravinder0003 said:
no its not true ... you can have cm9 with locket bootloader also
[ROM][UNLOCKED/LOCKED] • ParanoidAndroid ™ v1.4a XSola • [UNOFFICIAL][FXP207]
Latest cm9 for locked bootloders ... try this:good:
Click to expand...
Click to collapse
in that you have to manually use and edit atis112's guide to convert it your self from Unlocked BL to locked BL......
so it is advisable if you first search and then post.........
THANKS.......
Sony themselves told me that unlocking the bootloader on it's own doesn't void the warranty and neither does flashing roms necessarily. However if you brick the device etc whilst doing it then it would.
Also:
https://fsfe.org/freesoftware/legal/flashingdevices.en.html
Hi!
I want to root my active but I'm afraid that I can brick it or something.
I have it with the stock rom and the compilation number is 4.0.2.A.0.84.
Can I follow this tutorial? http://forum.xda-developers.com/showthread.php?t=2118343
Or there is one specific for the version I have?
Sorry if this has been asked before but it's not very clear for me what to do to root the phone.
Thanks!
I would advise you to read my rooting guide (in the stickies in general forum) and to follow the method for 4.0.2.A.0.62. It's really easy, but instead of updating to .62 you will update over the air to .84 (I hope that's working!)
Sent from my Nexus 4 running Android 4.3
mihahn said:
I would advise you to read my rooting guide (in the stickies in general forum) and to follow the method for 4.0.2.A.0.62. It's really easy, but instead of updating to .62 you will update over the air to .84 (I hope that's working!)
Sent from my Nexus 4 running Android 4.3
Click to expand...
Click to collapse
It's this one? http://forum.xda-developers.com/showthread.php?t=1842366
zephiruspt said:
It's this one? http://forum.xda-developers.com/showthread.php?t=1842366
Click to expand...
Click to collapse
Yes, that's right
You could use the tutorial for .62 or you simply try the program called "eroot"
Sent from my Nexus 4 running Android 4.3
Nothing to very about brother.:good:
First of all unlock your bootloader via sony`s official website. (i will give the link in .txt file)
Second flash any kernal via flashtool make sure you choose carefully between android versions i.e. use ICS kernal if you are on ICS,similarly GB kernal for GB and JB kernal for JB .
DONE..!!:highfive: I am not responsible for any harm to your device do it at your own risk
Hit thanks if i helped
mustufa_kheroda said:
Nothing to very about brother.:good:
First of all unlock your bootloader via sony`s official website. (i will give the link in .txt file)
Second flash any kernal via flashtool make sure you choose carefully between android versions i.e. use ICS kernal if you are on ICS,similarly GB kernal for GB and JB kernal for JB .
DONE..!!:highfive: I am not responsible for any harm to your device do it at your own risk
Hit thanks if i helped
Click to expand...
Click to collapse
Why should he unlock and void his warranty by unlocking just to root? That's not necessary
Sent from my Nexus 4 running Android 4.3
Its the easiest way
mihahn said:
Why should he unlock and void his warranty by unlocking just to root? That's not necessary
Sent from my Nexus 4 running Android 4.3
Click to expand...
Click to collapse
Unlocking bootloader and then rooting is the easiest way, unlocked bootloader will also provide manual settings of frequency which will indeed boost the phone. :good:
Root will avoid the warranty isn`t it . so whats the deal with unlocking the bootloader.
mustufa_kheroda said:
Unlocking bootloader and then rooting is the easiest way, unlocked bootloader will also provide manual settings of frequency which will indeed boost the phone. :good:
Root will avoid the warranty isn`t it . so whats the deal with unlocking the bootloader.
Click to expand...
Click to collapse
Unlocking is not the easiest way and it's not necessary. You are able too root without unlocking (check my guide, there are many methods) and you won't void your warranty, because after reflashing the stock rom, you can send it to the service center and Sony won't notice that it was rooted
Sent from my Nexus 4 running Android 4.3
Helpfull
mihahn said:
Unlocking is not the easiest way and it's not necessary. You are able too root without unlocking (check my guide, there are many methods) and you won't void your warranty, because after reflashing the stock rom, you can send it to the service center and Sony won't notice that it was rooted
Sent from my Nexus 4 running Android 4.3
Click to expand...
Click to collapse
Ya your guide is really helpfull and can root the phone without unlocking the phone. nice work sir...:good:
Well, first of all, many thanks for your contributions. Now I'm more confused. The main goal for me is to be able to free some internal space (remove stock applications?) Flashing custom ROM's is something I would like to but not necessary for now. So... for my first goal, I don't need bootloader unlock???
Added a question
mustufa_kheroda said:
Ya your guide is really helpful and can root the phone without unlocking the bootloader. nice work sir..:good:
But there is a question can we adjust the cpu frequencies without unlocking the bootloader?
---------- Post added at 02:46 PM ---------- Previous post was at 02:35 PM ----------
zephiruspt said:
Well, first of all, many thanks for your contributions. Now I'm more confused. The main goal for me is to be able to free some internal space (remove stock applications?) Flashing custom ROM's is something I would like to but not necessary for now. So... for my first goal, I don't need bootloader unlock???
Click to expand...
Click to collapse
Its up to you whether you want a locked bootloader or unlocked bootloader. If you use a locked bootloader you will be able to flash custom Roms but you will not be able to flash custom kernals. custom kernal basically will increase your phones performance.
Its your phone your choice brother.. Both the method are Perfect. My personal opinion is that you should use the rooting method with locked bootloader hence, it will not avoid your warranty (if you flash the stock rom again after flashing a custom Rom).
Click to expand...
Click to collapse
mustufa_kheroda said:
mustufa_kheroda said:
Ya your guide is really helpful and can root the phone without unlocking the bootloader. nice work sir..:good:
But there is a question can we adjust the cpu frequencies without unlocking the bootloader?
---------- Post added at 02:46 PM ---------- Previous post was at 02:35 PM ----------
Its up to you whether you want a locked bootloader or unlocked bootloader. If you use a locked bootloader you will be able to flash custom Roms but you will not be able to flash custom kernals. custom kernal basically will increase your phones performance.
Its your phone your choice brother.. Both the method are Perfect. My personal opinion is that you should use the rooting method with locked bootloader hence, it will not avoid your warranty (if you flash the stock rom again after flashing a custom Rom).
Click to expand...
Click to collapse
Ok, I will do that. Later if I need I will unlock the bootloader.
Click to expand...
Click to collapse
zephiruspt said:
Ok, I will do that. Later if I need I will unlock the bootloader.
Click to expand...
Click to collapse
That's the best way
If you have any further issues, just ask
Sent from my Nexus 4 running Android 4.3
mihahn said:
That's the best way
If you have any further issues, just ask
Sent from my Nexus 4 running Android 4.3
Click to expand...
Click to collapse
Hi mihahn,
I only had time to do this now and started looking at your thread and I need your help. Do I have to make all those steps described in section 2? Can you help me on this one?
zephiruspt said:
Hi mihahn,
I only had time to do this now and started looking at your thread and I need your help. Do I have to make all those steps described in section 2? Can you help me on this one?
Click to expand...
Click to collapse
Just try eroot first, it's the tool "for all firmware versions". It should work well! Download the tool and follow the instructions
Sent from my Nexus 4 running Android 4.3
mihahn said:
Just try eroot first, it's the tool "for all firmware versions". It should work well! Download the tool and follow the instructions
Sent from my Nexus 4 running Android 4.3
Click to expand...
Click to collapse
I tried eroot without success so I upgraded to 4.1.B.0.587. No success with eroot...
zephiruspt said:
I tried eroot without success so I upgraded to 4.1.B.0.587. No success with eroot...
Click to expand...
Click to collapse
Did you try it on .587 too?
If it's really not working, use the method for .587. There's a link to a tutorial by Abhinav2 and it should work then
simple explain
root mean u get permission to do something on app
"permission" that u give to app have the risk
milktea93 said:
root mean u get permission to do something on app
"permission" that u give to app have the risk
Click to expand...
Click to collapse
Thanks! Root done
Congratulations....
Sent from my Live with Walkman using xda app-developers app