iphone restore impossible. Error 21

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I tried to update the software on my iphone 4S today. It stopped working, & now won't even restore - I get "the iphone could not be restored. An unknown error occurred (21)'

It's a completely unhacked/jailbroken iphone, & I have the latest version of itunes (10.6.1), & run the latest OS X (10.7.4).

A bit of googling suggests that it might be firewalls or some such might be blocking the connection, but I don't have one of these.

Any ideas?
 
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13in rMBP 2014 Yosemite
what does iTunes say when you plug it into the computer?
does it say anything?
 

Jro


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what does iTunes say when you plug it into the computer?
does it say anything?


the iphone could not be restored. An unknown error occurred (21)

Try putting the phone into DFU mode and see if you can restore it.
 
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Still getting error 21

I've tried using DFU mode several times, but keep going round in circles.

I put the iphone in DFU mode (carefully monitoring the 10 seconds), iTunes gives the message "iTunes has detected an iPhone in recovery mode. You must restore this iPhone before it can be used with iTunes".
I click "ok", then "restore".
ITunes asks me if I am sure, I click "restore & update".
After a 10 - 15 seconds I get "the iphone "iphone" could not be restored. An unknown error occurred (21)."
 
C

chas_m

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Sounds like what happened is that you started an update but it didn't finish for whatever reason and so in a practical sense you've bricked it.

You'll need to see an Apple technician to sort that out.
 
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Still getting error 21

Thanks for the tip, for I really am getting nowhere (other than frustration city)

Next question: is the resetting of the iPhone to factory settings a straightforward operation for a mac technician? I am outside my home country, so could I just walk in to a mac shop & get it done (ok perhaps a bit of a wait), or is it a more complex operation requiring more time, production of warranties etc?
 
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chas_m

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No, should be a very straightforward operation. Make sure you go to a genuine Apple retail store OR a genuine Apple Authorised Service Provider (AASP) in whatever country you're in.
 

Jro


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I'm curious, since he's outside of the country of purchase would an Apple store from another country offer any type of assistant?
 

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