iPhone Restore Error on iTunes (Unknown Error 1)


macrumors newbie
Original poster
Mar 10, 2010
I purchased an iPhone 4 on Ebay which had a restore error and a bad battery (No water damage). I thought the restore error was due to a bad battery so I replaced the battery and tried to restore the phone and got an unknown error 1. I tried on another computer and received the same error.

Now I've used Redsn0w and used the "recovery fix" option and gotten the phone to boot. Then I used Redsn0w and jailbroke because I do not have a SIM at the moment and the phone fired up without issues. I even have a baseband and IMEI. I just haven't tested calls because I won't have access to an AT&T SIM for a couple weeks. Any ideas on why iTunes is throwing this error?

Version: 5.1.1 (9B208)
Carrier: Not Available (No SIM in phone)
Model: MC318LL
IMEI: xx xxxxxx xxxxxx x (They are digits but hidden for security purposes)
Modem Firmware: 04.12.01


macrumors member
Apr 23, 2012
Im in the same boat as u - itunes error 1... Do let me know if u tackle the problem..


macrumors 601
Oct 13, 2010
Error 1
You are attempting to downgrade an iPhone from iOS 5 to iOS 4.x. To resolve, use either custom firmware created by PwnageTool/sn0wbreeze or use notcom's FixRecovery utility available on his site.
On an iPhone 4 downgrading from iOS 5, use the option in TinyUmbrella to allow a baseband "upgrade" to bypass the error and go back to basband 4.10.1.
Unable to downgrade. Try changing the USB port (the back one of chassis is better) and restart computer.
The installed version of iTunes may also be too old. Update iTunes.
You are trying to downgrade an iPhone 4 to an earlier version of iOS 5, using redsn0w. To resolve, stitch your blobs to a "No_BB" ipsw of the firmware you are trying to downgrade to.


macrumors member
Apr 23, 2012
Im not on custom fw - im on 5.1.1 original firmware. And restoring back to original 5.1.1 fw..

I think it maybe hardware related such as baseband not being flashed correctly by the looks of my the update log report


macrumors 6502
Apr 1, 2011
Oslo, Norway
Try to empty your Hosts file (all but the one default line)
remember you need to have an internet connection
then do a DFU restore.

if that doesn't work,
try another usb port
the next step after that would be to try another computer