Can't upgrade to 2.1 on iPhone

[Xarea]

I have an unlocked 2.0 iPhone (unlocked/jailbroken with QuickPwn) and I can't seem to update to 2.1.

It's at the backup stage... it goes to take a backup, then gets about half way through, then I get the error:

iTunes could not sync ^0 to the iPhone because an unknown error occurred (-21).

Now, i've tried Google - no avail. I've tried to remove all the data and start again, but it fails on the backup. I've tried to restore, but still nothing happens.

I can't take it to my local Apple store 'cause it's, well, unlocked. Any help? Thanks!

[StefanCampbell1]

Force it into reboot mode/DFU mode, hold down home button for 5 seconds
then hold down the power button whilst still holding the home button for 10 seconds EXACTLY, just time your self counting in your head, then let go of the POWER button and still keep your finger pushed down on the home button for another 10 seconds, then plug it into your PC and it will be in restore mode.

[DaveTaylor]

2.1 jailbroken is unstable at the moment.

[Frizzoo]

I think i had the same problem, but then i unplugged it, connected again, and let it take back-up and then i could update it.

[Recursion]

2.1 Jailbreak has been perfect for me Dave? :S

[StefanCampbell1]

I've not bothered with the 2.1 jailbreak yet, i'm still on 2.0.1 jailbreak. Don't wanna' loose my crash bash rally highscores =[ lol.

[Verrou]

2.1 jailbroken is unstable at the moment.

Jailbroken 2.1 is quite stable actually.

[Xarea]

Fixed it... I had to wipe, upgrade, jailbreak, reload data back.