Restore error 21 and not eligible for requested build

Discussion in 'iPhone Tips, Help and Troubleshooting' started by ngrant, Apr 20, 2012.

  1. ngrant macrumors newbie

    Apr 19, 2012
    Hi all,

    I've got a factory unlocked iphone 4 running 5.0.1 and it's jailbroken. I wanted to restore my phone to factory settings. But everytime i try i get error 21, i then read stuff about modifying your hosts file and i've done it.

    Now it just says that phone is not eligible for the requested build. I've also tried restoring from another account but it says the same thing.

    I've also tried putting my phone in DFU but then i got error 1600??

    I'm kinda stuck and dunno what else to do, can someone please help me. I did install some cydia package to get siri on my phone and then installed spire also, in case these were causing any problems i've removed them, but it didn't change anything in Cydia.

    Iphone 4 GSM
    Version 5.0.1 (9A405)
    Model MC603B
    Firmware 04.11.08
  2. Shohan macrumors newbie

    Mar 27, 2011
    I wanted to restore recently myself so maybe what I did will work for you. Though, I have a VZW iPhone 4, did this on my MBP, I can't guarantee it will work and standard disclaimer of this is at your own risk. Here's the basics of what I did:

    Downloaded the latest Redsn0w and TinyUmbrella.
    Downloaded the IPSW file for 5.0.1
    Use TinyUmbrella to grab your SHSH blobs
    Use Redsn0w to stitch your SHSH blob and IPSW together
    Have TinyUmbrella modify your host file and start the TSS server
    Use Redsn0w to put your phone into pwned DFU mode
    In iTunes use the option key and click the Restore button to be able to select the IPSW file created earlier.
    Let it run.
    Note: the restore will be reported as failed and the phone won't boot properly
    Use Redsn0w to fix the boot recovery

    After I did this my phone booted correctly to a clean 5.0.1 load. I'd say do some research into each of those steps if you're not familiar with any of it. It was the first time I've done them and I was a bit anxious after my phone wouldn't boot properly.

    Good luck.
  3. darthcheezy macrumors newbie

    Apr 26, 2012
    How to downgrade iphone 5.1 to 5.0.1 without shsh blobs?

    ok ive got an iphone 4 with 5.1 ive tried for hours trying to find a way to downgrade so i can jailbreak it. ive tried changing the host file several times even tried deleting the ip address altogether but i still get the error that its not eligible for request build. can anyone help me!!

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