Limited Upgrade of 3GS from 4.1 to 4.2.1

Discussion in 'iPhone Tips, Help and Troubleshooting' started by OLight, Jul 15, 2012.

  1. OLight macrumors newbie

    Jul 15, 2012
    Hey folks...

    I'm trying to upgrade a 3GS on 4.1 (BB 05.14.02) to 4.2.1 *and no further*. Basically, I'm trying to use as low of a version of iOS to keep the device as lean as possible; I figure once I get newer and newer firmware, the hardware will be less and less able to support it without lag. I need 4.2+ only to run the app for my Nest thermostat.

    I've downloaded the IPSW (8C148), backed the device up, hit shift-Update and pointed to the IPSW I've downloaded, but always get the same message: "The iPhone "(name)" could not be updated. An unknown error occurred (3194)."

    I have the feeling I'm missing something simple. Can someone point it out to me, or tell me how else I'm doing it wrong? TIA!
  2. Shamil macrumors newbie

    Jul 17, 2012
    you can only upgrade iphone 3GS to IOS 5.1.1.

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