error 1600 and 21

Discussion in 'iPhone Tips, Help and Troubleshooting' started by harold1, Dec 28, 2011.

  1. harold1 macrumors newbie

    Dec 28, 2011
    Keep getting itunes error 1600 when trying to upgrade with pwn DFU and error 21 when trying to upgrade with restore mode. Can not figure how can I upgrade to 5.01 from 5.0. Any ideas? I
    Tried 2 computers, no luck.

    I have the same problem as the dude above except mine os occurring when trying to upgrade ios4.1 to 5.01. anyone have any ideas?
  2. Sly3GS macrumors newbie

    Jan 2, 2012
    Using my wires MacBook helped

    Hi Harold1,

    I seem to have had a similar problem.
    When trying to upgrade from a iPhone 3GS 4.3.3 to iOS5 (I had installed Cydia months ago, never used it and I felt it did not work properly (lost app icons, progress indicator everywhere)) and thus wanted to completely wipe and upgrade it.
    When trying from my own Mac, I run into the vicious "Error 21 -> maintenance mode" cycle which forced several reboots and always ended up again in maintenance mode. I saw my iPhone already in iPhone heaven.

    On my Mac also TinyUmbrella is installed, so maybe some hostlists have been altered which may cause this issue.

    After several fruitless attempts I simply connected the 3GS to my wife's MacBook and there iOS 5 was downloaded and installed without any problems. I now kept it as "new" iPhone but re-established the link to my iTunes library.
    So far everything fine. I guess TinyUmbrella and Cydia somehow cause issues.

    Best regards,
  3. porsche928 macrumors newbie

    Jan 4, 2012
    Hosts file!!!

    THanks Guys, basically I pulled the hair outta my head for a good few hours into the night ... till I saw the above post and recalled that I had once in a previous life jailbroken my iPhone3 and set my hosts file up. Once I commented out the old Cydia server in the file, I was able to restore in iTunes ... (was getting both 21 and 1600 errors btw) CHEERS!!!!

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