If you are getting Error 21 or Error 1600 while downgrading your iPhone, then the problem is that you are ending up in m Recovery Mode and not in a DFU mode. Make sure that you follow the instructions available at theBigBoss to get into DFU mode:
You got to do a normal restore to previous firmware via iTunes and then put your iPhone into DFU mode, and only then you need to follow the instructions to downgrade your iPhone from OS 3.1 or 3.0.
Over to BigBoss:
DFU (Device Firmware Upgrade) mode is not the same as restore mode. DFU mode bypasses the current OS installed and allows you to upgrade or downgrade your OS.
Recovery mode has a picture that says connect to iTunes. In DFU mode, the iPhone screen backlight is not even on and the display is blank. If you have anything on your display you are not in DFU mode.
This is how to achieve DFU mode. You can do it on every phone:
Method (1)
* Attach the phone to the pc
* Turn the phone off
* Hold power and home together for *exactly* 10 seconds
* Release power but keep holding home until the pc beeps as a USB device is recognized.
* At no point will the display come on. Now your restore should work.Having problems? Try adjusting the 10 seconds to be slightly less like 9 seconds, then 8, then 7. It’s a tricky timing but you will eventually get it.
Method (2)
* Hook up the phone powered on to the PC
* Now hold home / power until the phone turns off and keep holding for 10 seconds. If the phone ever turns on during this phase,start over and hold for less time.
* Now release power and continue holding home until the PC recognizes the phone.
* I don’t like this method as much because there are “rumors” that it may cause some 1604 errors in the restore. I am not convinced of that though.Method (3)
* Attach the phone to the pc
* Turn the phone off
* Press and hold power. Keep holding power. As soon as you see display on the screen of any sort press and hold home.
* Hold power and home together for *exactly* 10 seconds
* Release power but keep holding home until the pc beeps as a USB device is recognized.
* At no point will the display come on. Now your restore should work.Having problems? Try adjusting the 10 seconds to be slightly less like 9 seconds, then 8, then 7. It’s a tricky timing but you will eventually get it.
[via - BigBoss]
Thank yOU SO MUCH
I got itunes error 21 so i put it in DFU mode this time and got 1600.. now what i have itunes updated and i am on a 4.2.1 and want to be on a 5.0.1
stuck in the ‘Verifying iPod restore with apple’
heyy, i have a tethered ipod 4gen 8gb ipod touch. the last time that the battery ran out, it turned off. now i tried to boot my ipod and the process worked until my ipod bott. it says stuck at the pineapple logo and then suts off then returnes to the apple logo. i really need my ipod? ASAP so can anyone tell me how to fix this problem without restoring my device. thank you
you said put it to the same folder. but where is that?
please help me!!
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Hello humans!
I never saw anything more stupid!
I got errors because of the file.
21 and 1600 and 1601
File assembled by snowbrease 2.3b1
I put file on desktop, and itunes made me crazy with those errors.
after i let itunes download an update from it’s server, there were no problem.
i had updated ipad. but i needed cydia.
now to the point:
let snowbriz convert you image. USE SAME NAME AS ITUNES USES IT. AND PUT IT TO SAME FOLDER!!!
only after this make shift+restore!
it worked for me. hope it will help to others!
cheers!
Ty for this post error 21 for me was indeed because i was not in dfu mode
Got a solution, on Windows Vista with 3GS phone.
I created a new user in the control panel, restarted, then logged in as the new user.
I then opened iTunes, which installs for the new user and then connected the phone. It then went through the OS software update no problems.
I stopped it at registering/setting up and switched back to my original user profile and it automatically restored from the back up.
Hope this helps – amazing how lost you feel when your phone packs in :-/
I was getting Error 21 even in DFU mode. I logged in as a guest and then restored and it work just fine straight off. seems like there are a lot of setting that can go wrong.
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I have tried this it downloaded into a file budt nothing has happene
Tried all 3 methods, still getting the error 21 message.
I wasn’t trying to downgrade or jailbreak. I was trying to update from 3. something to ios 4 went into recovery mode, can’t get it back out no matter what I try.
thanks for this info…
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Hey Guys!
My problem is when I put my iphone into recovery mode nothing shows up in itunes. I don’t get window to restore! when i do it in dfu mode i always get the error 1600!
Many wishes and hope somebody can help!
Max
Download 3.0 firmware ipsw file from
1. http://bit.ly/F3UPR
or
2. http://bit.ly/t72KP
Where did you get the 3.0 firmware to downgrade to from apples 3.1?
Cool.. this confusion occurs everytime one tries to enter DFU mode. Good that you cracked this one
OMFG TY SOOOOOOOOOOOO MUCH IV BEEN TRYING FOR HOURS TO DOWNGRADE FROM 3.1 TO 3.0 AND I WAS IN RESTORE MODE THE WHOLE TIME